Herzog / Into the Inferno / Humans and Volcanoes

Go watch this on NETFLIX. “Odd” human behavior against the backdrop of spectacular volcanic forces. Don’t miss segment on north Korea…

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Genome Study Revises Neanderthal, Denisovan, “Modern” Lineages

 

New look at archaic DNA rewrites human evolution story

Contradicts convention on Denisovans, Neanderthals, modern humans

https://www.sciencedaily.com/releases/2017/08/170807155158.htm

Date: August 7, 2017

Excerpt: Previous estimates of the Neanderthal population size are very small — around 1,000 individuals. However, a 2015 study showed that these estimates underrepresent the number of individuals if the Neanderthal population was subdivided into isolated, regional groups. The Utah team suggests that this explains the discrepancy between previous estimates and their own much larger estimate of Neanderthal population size.

“Looking at the data that shows how related everything was, the model was not predicting the gene patterns that we were seeing,” said Ryan Bohlender, post-doctoral fellow at the M. D. Anderson Cancer Center at the University of Texas, and co-author of the study. “We needed a different model and, therefore, a different evolutionary story.”

The team developed an improved statistical method, called legofit, that accounts for multiple populations in the gene pool. They estimated the percentage of Neanderthal genes flowing into modern Eurasian populations, the date at which archaic populations diverged from each other, and their population sizes.

These population trees with embedded gene trees show how mutations can generate nucleotide site patterns. The four branch tips of each gene tree represent genetic samples from four populations: modern Africans, modern Eurasians, Neanderthals, and Denisovans. In the left tree, the mutation (shown in blue) is shared by the Eurasian, Neanderthal and Denisovan genomes. In the right tree, the mutation (shown in red) is shared by the Eurasian and Neanderthal genomes.

A family history in DNA

The human genome has about 3.5 billion nucleotide sites. Over time, genes at certain sites can mutate. If a parent passes down that mutation to their kids, who pass it to their kids, and so on, that mutation acts as a family seal stamped onto the DNA. Scientists use these mutations to piece together evolutionary history hundreds of thousands of years in the past. By searching for shared gene mutations along the nucleotide sites of various human populations, scientists can estimate when groups diverged, and the sizes of populations contributing to the gene pool.

“You’re trying to find a fingerprint of these ancient humans in other populations. It’s a small percentage of the genome, but it’s there,” said Rogers.

They compared the genomes of four human populations: Modern Eurasians (living today), modern Africans, Neanderthals and Denisovans. The modern samples came from Phase I of the 1000-Genomes project and the archaic samples came from the Max Planck Institute for Evolutionary Anthropology. The Utah team analyzed a few million nucleotide sites that shared a gene mutation in two or three human groups, and established 10 distinct nucleotide site patterns.

Against conventional wisdom

The new method confirmed previous estimates that modern (living today) Eurasians share about 2 percent of Neanderthal DNA. However, other findings questioned established theories. Their analysis revealed that 20 percent of nucleotide sites exhibited a mutation only shared by Neanderthals and Denisovans, a genetic timestamp marking the time before the archaic groups diverged. The team calculated that Neanderthals and Denisovans separated about 744,000 years ago, much earlier than any other estimation of the split. (Was the last common ancestor Homo erectus?)

“If Neanderthals and Denisovans had separated later, then there ought to be more sites at which the mutation is present in the two archaic samples, but is absent from modern (living today) samples,” said Rogers. The analysis also questioned whether the Neanderthal population had only 1,000 individuals. There is some evidence for this; Neanderthal DNA contains mutations that usually occur in small populations with little genetic diversity. However, Neanderthal remains found in various locations are genetically different from each other. This supports the study’s finding that regional Neanderthals were likely small bands of individuals, which explains the harmful mutations, while the global population was quite large.

“The idea is that there are these small, geographically isolated populations, like islands, that sometimes interact, but it’s a pain to move from island to island. So, they tend to stay with their own populations,” said Bohlender.

Their analysis revealed that the Neanderthals grew to tens of thousands of individuals living in fragmented, isolated populations.

“There’s a rich Neanderthal fossil record. There are lots of Neanderthal sites,” said Rogers. “It’s hard to imagine that there would be so many of them if there were only 1,000 individuals in the whole world.”

Rogers is excited to apply the new method in other contexts.

“To some degree, this is a proof of concept that the method can work. That’s exciting,” said Rogers. “We have remarkable ability to estimate things with high precision, much farther back in the past than anyone has realized.”

Original Paper:

Early history of Neanderthals and Denisovans

Alan R. Rogers, Ryan J. Bohlender, and Chad D. Huff

http://www.pnas.org/content/114/37/9859

Neanderthal and Homo erectus (Turkana Boy – 1.5-1.6 mya) reconstructions by Elizabeth Daynes / Field Museum, Chicago. 

 

How to Exterminate Aboriginal Peoples / Re-Post

The idiotic European belief that dressing up indigenous people in "white" clothing will magically convert them into being "tame" or "domesticated."

The idiotic European belief that dressing up indigenous people in “white” clothing will magically convert them into being “tame” or “domesticated.” This same magical belief inspires the crazy idea that training Asperger children to mimic social behavior will make them acceptable to Neurotypicals. 

The extinction of aboriginal Tasmanians by Europeans is a believable model for the disappearance of many native populations worldwide.

I want to focus on a cause or strategy that we tend not to think about – the gender-based behavior that modern social humans follow when encountering indigenous populations.

The extinction of full-blooded Tasmanians is a seriously contentious topic and I’m not taking sides in the “who killed how many” debate. People take sides, of course, blaming imported diseases or the Christian need to rescue savages from barbarism and sin, or simple racist indifference – the conclusion is a terrible cliché. Aboriginal peoples disappeared because they were inferior to white people. Some insist that no ill-treatment on the part of white people occurred. All of these are truly dishonorable “weasel”  excuses.

We hear the claim of Homo sapiens superiority (white Europeans) also in the persistent belief that Neanderthals “failed” because they couldn’t compete; in a pseudo-Darwinian sense “they had to die.” 

Imported disease is the explanation given the most credit for aboriginal deaths, since it confers the absence of intent on the part of invading Europeans: The bringers of death turn out to be “victims of disease and therefore Good Christians after all.

Few quantitative records exist for death by disease events, and the estimates given for percentage of population lost in any given European – Native encounter are as flexible as the person writing an account needs them to be. In fact, we have very little data about the history of indigenous peoples, because the white people who triggered their demise thanked God for their disappearance. Unless the natives were suitable for enslavement, childbearing and forced labor, they were eliminated.

_____general information: Tasmanian

Tasmanian, any member of the extinct Australoid population of Tasmania. The Tasmanians were an isolate population of Aboriginal Australians, not a separate or distinctive population, who were cut off from the mainland when a general rise in the sea level flooded the Bass Strait about 10,000 years ago. Their population upon the arrival of European explorers in the 17th and 18th centuries has been estimated at about 4,000. They were a relatively short people, with generally Australoid physical characteristics. The Tasmanians spoke languages that were unintelligible to mainland Aborigines.
The island was divided among several tribes speaking different dialects, each with a delimited hunting territory. Subsistence was based on hunting land and sea mammals and collecting shellfish and vegetable food. In warm months the Tasmanians moved through the open forest and moorlands of the interior in bands or family groups of 15 to 50 people; in colder months they moved to the coast. Occasionally, bands gathered together for a corroboree (a dance celebrating important events), a hunt, or for protection against attack.Wooden spears, waddies (clubs, or throwing sticks), and flaked-stone tools and weapons were produced. Bone implements, basketry, and bark canoes for coastal travel were also made. A few rock carvings depicting natural objects and conventionalized symbols have survived.

The first permanent white settlement was made in Tasmania in 1803; in 1804 an unprovoked attack by whites on a group of Tasmanians was the first episode in the Black War. The whites treated the Aborigines as subhumans, seizing their hunting grounds, depleting their food supply, attacking the women, and killing the men. Tasmanian attempts to resist were met with the superior weaponry and force of the Europeans. Between 1831 and 1835, in a final effort at conciliation and to prevent the extermination of the approximately 200 remaining Tasmanians, the Aborigines were removed to Flinders Island. Their social organization and traditional way of life destroyed, subjected to alien disease and attempts to “civilize” them, they soon died. Truganini (d. 1876), a Tasmanian woman who aided the resettlement on Flinders Island, was the last full-blooded Aborigine in Tasmania. Another Tasmanian woman is said to have survived on Kangaroo Island in South Australia until 1888.

Gender Strategy to come, next post…

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Ancient Homo in the Philippines? / Two Articles Aye, yai, yai!

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Ancient humans settled the Philippines 700,000 years ago (as opposed to modern day humans)
http://www.sciencemag.org/news/2018/05/ancient-humans-settled-philippines-700000-years-ago-new-fossils-reveal
xx

“The only thing missing is the hominin fossil to go along with it,” says archaeologist Adam Brumm, of Griffith University in Nathan, Australia. He’s wasn’t involved with the work. (This standard “journalistic format” added comment by a “random” expert drives me nuts… is it supposed to compensate for lack of evidence? Is it merely to make it look like the journalist did some “background work”? Or is it the NT passion for “he said, she said” cable TV news “black and white” ideological warfare transferred to “science” articles? Please stop! 

Researchers found 75% of a fossilized rhino skeleton—ribs and leg bones still scarred from the tools that removed their meat and marrow—lying in ancient mud that had long since buried an even older river channel. To determine the site’s age, researchers dated the enamel in one of the rhino’s teeth, as well as quartz grains embedded in the sediment layers above and below the bones, using electron spin resonance (ESR), which measures the buildup of electrons as a material is exposed to radiation over time. The team dated the bottom sediment layer to about 727,000 years old, the rhino tooth to about 709,000 years old, and the top sediment layer to about 701,000 years old. Several independent experts say (aye, yai, yai!) they were impressed by the team’s careful use of the technique. “They’ve nailed it,” says Alistair Pike, an archaeological dating expert at the University of Southampton in the United Kingdom. (Please stop inserting these technically-scientifically irrelevant comments! These statements are NOT PROOF that the dating is accurate, EXCEPT IN THE “lazy-crazy” NT social brain. The appeal to “authorities” is a social substitute for facts; NTs believe in “authority hearsay” and don’t recognize the existence of factual information) 

So who were these ancient people? They couldn’t have been our own species, Homo sapiens, which evolved in Africa hundreds of thousands of years later. The most likely bet is H. erectus, an archaic human species that first evolved nearly 2 million years ago and may have been the first member of our genus to expand out of Africa, the team writes today in Nature. H. erectus bones have been found in China and Java, so researchers know they lived in Asia (Asia is a VERY BIG PLACE, but if one is geographically illiterate, this vague reference may sound impressive and “meaningful”) around the time the rhino was butchered on Luzon. But Thomas Ingicco, a paleoarchaeologist at the National Museum of Natural History in Paris who led the research, doesn’t want to jump to any conclusions without human bones—especially not in a region that already has yielded one big surprise for scientists studying archaic humans. (Drum roll…)

Three thousand kilometers to the south, (almost 2,000 miles) on the island of Flores in Indonesia, archaeologists discovered H. floresiensis, a diminutive archaic human species known as the hobbit. It lived from about 60,000 to 100,000 years ago and seems to have evolved its short stature, large feet, and other distinctive traits because of its long isolation on Flores. There’s no evidence that the rhino butcherers on Luzon are the ancestors of the hobbit, or connected to those unusual humans in any way. But the discovery of H. floresiensis opened up the possibility that there could be many hitherto unknown human species living and evolving in Southeast Asia. (Wow! What “peculiar” logic. 1. Why are “the Hobbits” even mentioned in this context? (700,000 y.o. hominid in Luzon “magically” connects to” 60-100,000 y.o. hominid in Flores, 3,000 km away. 2. The possibility of hitherto unknown human species living and evolving in Southeast Asia” already exists WITHOUT “the Hobbits”. 3. The salient fact about Flores Homo is that it’s small stature is a consequence of being isolated on an island – they were not “wandering around” a vast region.  “In theory you could have something special on every single island,” Ingicco says.

And how did the rhinoceros get to Luzon?

The area in question.

Equally mysterious (please ban the use of mysterious, strange, bizarre, etc. in science journalism, and let the Ancient Aliens crew have this nonsense as their very own ”catchy” theme! The use of mysterious, etc can only refer in this context to the confused state of the NT mind.) is how the ancestors of the rhino butchers arrived on Luzon, which was surrounded by deep water then, as it is today. “I’ve been studying H. erectus for a long time, and I think they are pretty clever,” says Susan Antón, a paleoanthropologist at New York University in New York City who wasn’t involved in the work. Recent research (by whom?) even suggests that stone age peoples were using boats more than 130,000 years ago in the Mediterranean Sea. (Now there is a piece of “NT logic” – Non-correlation of geography, dates, location – and zero evidence – are no obstacle to social typical magical thinking) But like most researchers Antón isn’t convinced that ancient humans were deliberately crossing Southeast Asian seas so long ago. More likely, they were carried to distant islands by tsunami waves, or arrived there via floating islands of land and debris detached during typhoons. (Really? Does this actually occur, or is this a garbled interpretation of massive landslides that end up AT THE BOTTOM OF THE SEA? Maybe it was Ancient Astronauts…) “The presumption has been that Homo erectus didn’t, at least purposefully, disperse over water,” Antón says. “But the more places you find that happening, then … the more likely it becomes that they had some kind of control over it. But that kind of a conclusion is way off in the distance.” (How articulate…)

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Let’s see what NATGEO has to say: 

700,000-Year-Old Stone Tools Point to Mysterious Human Relative

https://news.nationalgeographic.com/2018/05/stone-tools-rhinoceros-luzon-philippines-ancient-hominins-science/

Someone butchered a rhinoceros in the Philippines hundreds of thousands of years before modern humans arrived—but who?

Stone tools found in the Philippines predate the arrival of modern humans to the islands by roughly 600,000 years—but researchers aren’t sure who made them.

The eye-popping artifacts, unveiled on Wednesday in Nature, were abandoned on a river floodplain on the island of Luzon beside the butchered carcass of a rhinoceros. The ancient toolmakers were clearly angling for a meal. Two of the rhino’s limb bones are smashed in, as if someone was trying to harvest and eat the marrow inside. Cut marks left behind by stone blades crisscross the rhino’s ribs and ankle, a clear sign that someone used tools to strip the carcass of meat.

But the age of the remains makes them especially remarkable: The carved bones are most likely between 631,000 and 777,000 years old, with researchers’ best estimate coming in around 709,000 years old. The research—partially funded by the National Geographic Society—pushes back occupation of the Philippines to before the known origin of our species, Homo sapiens. (Of course, as the pinnacle of evolution, every “discovery” must be oriented to “our” arrival!) The next-earliest evidence of Philippine hominins comes from Luzon’s Callao Cave, in the form of a 67,000-year-old foot bone.

“It was surprising to find such an old peopling of the Philippines,” says lead study author Thomas Ingicco, an archaeologist with France’s National Museum of Natural History. While the researchers don’t know which archaic cousin of ours butchered the rhino, the find will likely cause a stir among people studying the human story in the South Pacific—especially those wondering how early hominins got to the Philippines in the first place.

“I think it’s pretty spectacular,” says Michael Petraglia, a paleoanthropologist at the Max Planck Institute for the Science of Human History who was not involved in the work. “While there had been claims for early hominins in places like the Philippines, there wasn’t any good evidence until now.”

Dating With Confidence

Several of the habitable islands across the South Pacific have long been hemmed off by swaths of open ocean, (Is that not what an island is?) so it was thought that humans’ ancient cousins couldn’t have made it to them without knowing how to sail.

But as the saying goes, life finds a way. In 2004, researchers unveiled Homo floresiensis, which lived on the isolated island of Flores for hundreds of thousands of years. In 2016, researchers also found stone tools on Sulawesi, an island north of Flores. As National Geographic reported at the time, the Sulawesi tools date to at least 118,000 years ago, or some 60,000 years before the first anatomically modern humans arrived. (Repetitive NT narcissism)

“It’s really, really exciting—it’s now becoming increasingly clear that ancient forms of hominins were able to make significant deep-sea crossings,” says Adam Brumm, a paleoanthropologist at Griffith University who studies H. floresiensis. (but wait…)

In search of similar sites, Ingicco and Dutch biologist John de Vos went to Kalinga, a site in northern Luzon with a reputation for yielding ancient bones. Researchers had found animal bones and stone tools there since the 1950s, but those scattered remains couldn’t be dated. To prove that ancient hominins had lived at Kalinga, de Vos and Ingicco needed to find artifacts that were still buried.

In 2014, the team dug a test pit at Kalinga about seven feet to a side. Almost immediately, the researchers started finding bones that belonged to a long-extinct rhinoceros. Soon, they had uncovered an entire skeleton, as well as stone tools left behind by its butchers.

To get an age range for the site, the team measured the sediments and the rhino’s teeth to see how much radiation they had naturally absorbed over time. (You never know – 700,000 y.a. there may have been time traveling H. sapiens going around artificially irradiating rhinoceros bones and teeth. Or maybe it was Ancient Aliens) In addition, they measured the natural uranium content of one of the rhino’s teeth, since that element decays like clockwork into thorium. In the mud around the rhino’s bones, they also found a speck of melted glass from an asteroid impact dated to about 781,000 year ago. (More magical and irrelevant NT type “evidence” What impact, where? How did it “end up” in the sediment? erosion, transport, etc.)

“Nowadays, it’s necessary that you try various methods to nail the dates, because in the past, there have been so many dates that have proved unreliable,” says study coauthor Gerrit van den Bergh, a University of Wollongong sedimentologist.

The Unusual Suspects

The list of possible toolmakers includes the Denisovans, a ghost lineage of hominins known from DNA and a handful of Siberian fossils. The leading candidate, though, is the early hominin Homo erectus, since it definitely made its way into southeast Asia. The Indonesian island of Java has H. erectus fossils that are more than 700,000 years old.

Ingicco’s team suggests that the butchers may have been Luzon’s version of H. floresiensis, (what on earth does that mean?) which may have descended from a population of H. erectus that ended up on Flores. Over millennia, the H. erectus there may have evolved to live efficiently on a predator-free island, shrinking in a process called island dwarfism.

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But wait! 

The most comprehensive study on the bones of Homo floresiensis, a species of tiny human discovered on the Indonesian island of Flores in 2003, has found that they most likely evolved from an ancestor in Africa and not from Homo erectus as has been widely believed.

The study by The Australian National University (ANU) found Homo floresiensis, dubbed “the hobbits” due to their small stature, were most likely a sister species of Homo habilis—one of the earliest known species of human found in Africa 1.75 million years ago.

Read more at: https://phys.org/news/2017-04-indonesian-hobbits-revealed.html#jCp

SEE also: http://www.dailymail.co.uk/sciencetech/article-4429596/Indonesian-hobbits-early-form-human.html

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back to: In 2010, a team led by University of Philippines Diliman archaeologist Armand Mijares found the Callao Cave foot bone, which has measurements that overlap with both modern humans and H. floresiensis. (Utterly meaningless: this panders to archaic notions of “linear evolution” that demands “missing links” – so outdated!) Was this Luzon hominin a homegrown hobbit, descended from H. erectus castaways that arrived hundreds of thousands of years before? It’s too soon to say. (OMG!)

“We don’t have any information about 600,000 years of prehistory, [so] it’s a reach,” says Petraglia. 

Riding Out the Storm?

Whoever they were, the toolmakers’ ancestors may have taken one of two migration routes into the Philippines, according to Ingicco’s team: an west-to-east route from Borneo or Palawan, or a north-to-south route from China and Taiwan. (Does this contrived “choice” have any real meaning? Were Homo erectus standing around looking at a map, arguing over which “migration route” to take?) But it’s an open question how these hominins crossed open ocean.

It’s tempting to think that our extinct cousins used rudimentary boats: When news of the Callao Cave remains broke in 2010, some experts chalked up their presence to ancient seafarers. But the idea is still considered farfetched. Rhinos and elephant-like creatures also made it to Luzon, and they clearly didn’t build boats.

OMG! What is this, a Disney movie?

Perhaps large animals and the butchers’ ancestors accidentally rode to Luzon on floating masses of mud and aquatic plants, torn off coastlines by large storms. Regional tsunamis may have also washed some terrified H. erectus out to sea. As they clung to floating debris, they may have inadvertently island-hopped.

“Water dispersal by H. erectus is accidental—there’s no Manifest Destiny, there’s no plot,” says Russell Ciochon, a paleoanthropologist at the University of Iowa at Iowa City. (What an outstanding contribution to this article!)

There’s also outstanding questions about what happened when and if descendants of these early hominins made contact with the first modern humans to reach Luzon: (Endless NT narcissism, of course.) “Did our species come face to face with these creatures? What is the nature of that contact?” wonders Brumm.

These and other questions remain to be answered, but researchers say that study of the human story in Luzon—and the South Pacific writ large—is only just beginning.

Zaworski’s Blog / Neanderthal – Archaic H. Sapiens

James Zaworski’s Blog

Much more at:  Morphological and Archaeological Comparisons of the Levantine Neandertal and Archaic Homo sapiens Complexes.

Morphological Traits and Variation.

It is imperative to my discussion here to set out the accepted morphological traits that defines how a Neandertal is classified , and how an Anatomically Modern Homo sapiens (AMHS), is classified. This is not as cut and dry as it seems. Depending on which paleoanthropologist is doing the analysis, there really isn’t an accepted laundry list of characteristic traits that are consistently used. When paleoanthropologists compare the morphology of Neandertals and AMHS, it is usually the case to compare the most robust or “classic” Neandertals from Western Europe with the most gracile “Cro-Magnon” Homo sapiens from Europe. This is not a fair comparison by a long shot, in terms of variation, because these two are on the complete opposite ends of the spectrum in terms of general skeletal and cranial robusticity on the one hand with the Classic Western European Neandertals and extreme skeletal and cranial gracility on the part of the Cromagnon. Where this becomes much more confusing is in the Levantine area of the Middle East, in the modern state of Israel, because the specimens that have been discovered at the various sites, such as Skhul, Amud, Qafzeh, Tabun, Kebara, and Mount Carmel all display characteristics that are intermediate in their morphological characteristics.(Wolpoff, 1999:594, 612). Further confusion comes into the picture, as the anatomically modern Homo sapiens have also been dubbed “proto-Cro-Magnons”, implying that these are indeed the true ancestors and precursors of modern Homo sapiens.(Bar-Yosef, 1988:31).

 

 

Modern Humans will eat anything / So did early hominids

 

Pyura Chilensis, contains 10 million times the level of vanadium than in the surrounding seawater. Just add a saucy slurry of tar polluting the beach. Or is that black stuff produced by the animal? Yum!

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Real Paleo Diet: early hominids ate just about  everything

https://theconversation.com/real-paleo-diet-early-hominids-ate-just-about-everything-36689

Postdoctoral Fellow in Primate and Human Evolution, Georgia State University

Reconstructions of human evolution are prone to simple, overly-tidy scenarios. Our ancestors, for example, stood on two legs to look over tall grass, or began to speak because, well, they finally had something to say. Like much of our understanding of early hominid behavior, the imagined diet of our ancestors has also been over-simplified.

Take the trendy Paleo Diet which draws inspiration from how people lived during the Paleolithic or Stone Age that ran from roughly 2.6 million to 10,000 years ago. It encourages practitioners to give up the fruits of modern culinary progress – such as dairy, agricultural products and processed foods – and start living a pseudo-hunter-gatherer lifestyle. Adherents recommend a very specific “ancestral” menu, replete with certain percentages of energy from carbohydrates, proteins and fats, and suggested levels of physical activity. These prescriptions are drawn mainly from observations of modern humans who live at least a partial hunter-gatherer existence.

But from a scientific standpoint, these kinds of simple characterizations of our ancestors’ behavior generally don’t add up. Recently, fellow anthropologist C. Owen Lovejoy and I took a close look at this crucial question in human behavioral evolution: the origins of hominid diet. We focused on the earliest phase of hominid evolution from roughly 6 to 1.6 million years ago, both before and after the first use of modified stone tools. This time frame includes, in order of appearance, the hominids Ardipithecus and Australopithecus, and the earliest members of our own genus, the comparatively brainy Homo. None of these were modern humans, which appeared much later, but rather our distant forerunners.

We examined the fossil, chemical and archaeological evidence, and also closely considered the foraging behavior of living animals. Why is this crucial? Observing animals in nature for even an hour will provide a ready answer: almost all of what an organism does on a daily basis is simply related to staying alive; that includes activities such as feeding, avoiding predators and setting itself up to reproduce. That’s the evolutionary way.

Scraping ancient teeth for clues about diet.

What did our ancestors actually eat? In some cases, researchers can enlist modern technology to examine the question. Researchers study the chemical makeup of fossil dental enamel to figure out relative amounts of foods the hominid ate derived from woody plants (or the animals that ate them) versus open country plants. Other scientists look in ancient tooth tartar for bits of silica from plants that can be identified to type – for example, fruit from a particular plant family. Others examine the small butchering marks made on animal bones by stone tools. Researchers have found, for example, that hominids even 2.6 million years ago were eating the meat and bone marrow of antelopes; whether they were hunted or scavenged is hotly debated.

Such techniques are informative, but ultimately give only a hazy picture of diet. They provide good evidence that plants’ underground storage organs (such as tubers), sedges, fruits, invertebrate and vertebrate animals, leaves and bark were all on the menu for at least some early hominids. But they don’t give us information about the relative importance of various foods. And since these foods are all eaten at least occasionally by living monkeys and apes, these techniques don’t explain what sets hominids apart from other primates.

So how should we proceed? As my colleague Lovejoy says, to reconstruct hominid evolution, you need to take the rules that apply to beavers and use them to make a human. In other words, you must look at the “rules” for foraging. We aren’t the first researchers to have dabbled in this. As long ago as 1953, anthropologists George Bartholomew and Joseph Birdsell attempted to characterize the ecology of early hominids by applying general biological principles.

Does American fast food qualify as “profitable foods” in optimal foraging theory? 

 

Happily, ecologists have long been compiling these rules in an area of research dubbed optimal foraging theory (OFT). OFT uses simple mathematical models to predict how certain animals would forage in a given circumstance. For instance, given a set of potential foods of estimated energetic value, abundance and handling time (how long it takes to acquire and consume), one classic OFT model calculates which resources should be eaten and which ones should be passed over. One prediction — sort of a “golden rule” of foraging — is that when profitable foods (those high in energy and low in handling time) are abundant, an animal should specialize on them, but when they are scarce, an animal should broaden its diet. (DUH!)

Data from living organisms as disparate as insects and modern humans generally fall in line with such predictions. In the Nepal Himalaya, for example, high-altitude gray langur monkeys eschew leathery mature evergreen leaves and certain types of roots and bark — all calorie-deficient and high in fibers and handling time — during most of the year. But in the barren winter, when better foodstuffs are rare or unavailable, they’ll greedily devour them.

In another more controlled study, when differing quantities of almonds in or out of the shell are buried in view of chimpanzees, they later recover larger quantities (more energy), those physically closer (less pursuit time), and those without shells (less processing time) before smaller, more distant, or “with-shell” nuts. This suggests that at least some animals can remember optimal foraging variables and utilize them even in cases where foods are distant and outside the range of immediate perception. Both of these studies support key predictions from OFT.

If one could estimate the variables important to foraging, one could potentially predict the diet of particular hominids that lived in the distant past. It’s a daunting proposition, but this human evolution business was never meant to be easy. The OFT approach forces researchers to learn how and why animals exploit particular resources, which leads to more thoughtful considerations of early hominid ecology. A smattering of scientists have utilized OFT with success, most notably in archaeological treatments of comparatively recent hominids, such as Neandertals and anatomically modern humans.

But a few brave souls have delved into more remote human dietary history. One team, for example, utilized OFT, modern analogue habitats, and evidence from the fossil record, to estimate the predicted optimal diet of Australopithecus boisei. That’s the famed “Nutcracker Man” that lived in East Africa close to 2 million years ago. The research suggests a wide range of potential foods, greatly varying movement patterns – based on characteristics such as habitat or use of digging sticks — and the seasonal importance of certain resources, such as roots and tubers, for meeting estimated caloric requirements.

Researchers Tom Hatley and John Kappelman noted in 1980 that hominids have bunodont – low, with rounded cusps – back teeth that show much in common with bears and pigs. If you’ve watched these animals forage, you know they’ll eat just about anything: tubers, fruits, leafy materials and twigs, invertebrates, honey and vertebrate animals, whether scavenged or hunted. The percentage contribution of each food type to the diet will depend (you guessed it) on the energetic value of specific foods in specific habitats, at specific times of year. Evidence from the entirety of human evolution suggests that our ancestors, and even we as modern humans, are just as omnivorous.

And the idea that our more ancient ancestors were great hunters is likely off the mark, as bipedality — at least before the advance of sophisticated cognition and technology — is a mighty poor way to chase game. Even more so than bears and pigs, our mobility is limited. The anthropologist Bruce Latimer has pointed out that the fastest human being on the planet can’t catch up to your average rabbit. Another reason to be opportunistic about food.

Simple characterizations of hominid ecology are divorced from the actual, and wonderful, complexity of our shared history. The recent addition of pastoral and agricultural products to many modern human diets — for which we have rapidly evolved physiological adaptations — is but one extension of an ancient imperative. Hominids didn’t spread first across Africa, and then the entire globe, by utilizing just one foraging strategy or sticking to a precise mix of carbohydrates, proteins and fats. We did it by being ever so flexible, both socially and ecologically, and always searching for the greener grass (metaphorically), or riper fruit (literally).

Article on Jebel Irhoud 300 K fossils / Participating researcher

New Moroccan fossils suggest humans lived and evolved across Africa 100,000 years earlier than we thought

by Senior research fellow, Southern Cross University

https://theconversation.com/new-moroccan-fossils-suggest-humans-lived-and-evolved-across-africa-100-000-years-earlier-than-we-thought-78826

See original for photos

The earliest known existence of modern humans, or Homo sapiens, was previously dated to be around 200,000 years ago. It’s a view supported by genetic analysis and dated Homo sapiens fossils (Omo Kibish, estimated age 195,000 years, and Herto, estimated age 160,000 years), both found in modern-day Ethiopia, East Africa.

But new research, published today in two Nature papers, offers a fresh perspective. The latest studies suggest that Homo sapiens spread across the entire African continent more than 100,000 years earlier than previously thought.

This evidence pushes back the origins of our species to 300,000 years ago, and supports the idea that important changes in our biology and behaviour had already taken place across most of Africa by that time.

Our work focused on samples collected at the archaeological site Jebel Irhoud in Morocco. It’s a place that is well known for hominin fossils – that is, bones from early humans – first excavated in the 1960s.

However, the interpretation of the first fossils and identification of their age was compromised previously, due to uncertainty about the geological dating of the sediment layers in which the remains had been found.

More than 40 years later, in 2004, an international team of scientists reopened the excavation. They discovered 16 new Homo sapiens fossils and a large number of Middle Stone Age artefacts. Now in 2017 we’re able to report on these remains thanks to improved dating techniques.

The new analysis proposes a revised version of the evolutionary history of modern humans that involves the entire African continent, and long before the “out-of-Africa” spread of Homo sapiens to other continents (dated at around 100,000 years ago).

Jebel Irhoud is the richest African Middle Stone Age site associated with the earliest known representative of our species.

Bones with modern and ancient features

The fossil remains excavated included numerous skulls and jawbones, long bones such as femur (from the leg) and humerus (from the arm), and teeth of several individuals. They reveal a mixture of modern human and more archaic, or ancient, features.

Of particular note is the slim, “gracile” face seen in living humans, which is also present in Jebel Irhoud specimens. Compared with the more robust face and elongated skull of Neanderthals or older hominins, the faces of Jebel Irhoud specimens are slender, relatively short, and sit under a rounder braincase (the part of the skull in which the brain sits).

However, while tomographic scans (which create 3D images through digital sectioning) reveal that the facial shape in the fossil samples is practically indistinguishable from humans nowadays, there are differences in the skull structure. In particular, the structure of the cranium, or skull bone, is different.

Compared with modern humans, in the Jebel Irhoud specimens we see a more elongated shape of the braincase, plus elongated temporal bones (on the sides of the skull, forming the temple), flatter parietal bones (along the sides and top of the skull) and different occipital shape (at the rear of the skull). This results in a longer and lower braincase.

Anatomically, this analysis places the 300,000-year-old Jebel Irhoud Homo sapiens somewhere between Homo erectus and African archaic Middle Pleistocene hominins. In this way it challenges the hypothesis that Homo sapiens derived from a later intermediate species that lead to the emergence of both the modern human and Neanderthal lineages.

These differences have implications for our understanding of Homo sapiens evolution. They suggest that our facial shape was established early in our history, whereas certain cognitive functions may have appeared later with the evolution of the Homo sapiens lineage and modifications of the braincase.

How we dated the Jebel Irhoud samples

In addition to the fossils, stone artefacts found at the Jebel Irhoud site consisted of Middle Stone Age material of Levallois technology (a distinct method of creating stone tools), with a high proportion of retouched tools, especially pointed forms.

Materials from Jebel Irhoud were accurately dated using two distinct techniques.

Thermoluminescence (TL), which works by measuring the irradiation dose received from the surrounding sediment since the material was last exposed to heat or fire, was applied to the stone artefacts.

Techniques known as Coupled Uranium-Series and Electron Spin Resonance (together referred to as US-ESR) were applied to the fossil remains directly. By calculating the diffusion of natural elements (uranium and thorium) into the dental tissues as fossilisation occurred over time, combined with the amount of surrounding radiation from the sediment the enamel crystal has been exposed to, we are able to work out the burial time of the remains.

While TL established clearly a chronology for the sediment layers which contained the hominin fossil remains, the US-ESR dates gave a direct age of one of the Jebel Irhoud jawbones (Irhoud 3 mandible). This was possible through new high-resolution radioactivity measurements of the geological context and important methodological improvements which allowed us to understand the impact of irradiation onto the tooth enamel crystal structure.

Both dating of the jaw bone and the dating of the stone artefacts gave us an age of 300,000 years.

A complex human journey

The new find is consistent with a picture of complex, Africa-wide origin of Homo sapiens.

The observed skull shapes and calculated ages of the bones and tools have implications for interpreting other human-like fossils found in Africa. The enigmatic partial skull of Florisbad from South Africa is also a very important Middle Stone age sample, and presents a mix of modern and ancient features.

Whether Florisbad should be classified as Homo heidelbergensis or Homo helmei has been a subject of prolonged debate. But with the anatomical features observed in Jebel Irhoud specimen, Florisbad skull can be more securely described as an early Homo sapiens form.

This discovery is also interesting in light of the newly dated Homo naledi from South Africa. This species, which survived until 250,000 years ago, overlaps in time with the Jebel Irhoud specimens. As Homo naledi represents a different branch of the genus Homo (not a direct ancestor to Homo sapiens), this is evidence that more archaic forms of hominins coexisted with the early representative of our species.

Similarly, Homo erectus Salé – also discovered in Morocco, not far from Jebel Irhoud – dates back to 250,000 years ago and might have coexisted with the early form of Homo sapiens, although the identification and age of the Salé specimen remains highly debated.

More than ever, as humans our complex evolutionary journey to end up as the lone surviving hominid species appears to be anything but linear. With African archaic Middle Pleistocene hominins overlapping in time with the Jebel Irhoud specimens, our discovery advocates for a complex African-wide evolutionary history of Homo sapiens. This new evidence adds more detail to the debate around the birthplace not only for our species, but also for the entire genus homo.

The famous drawing of a linear and simplistic evolution from ape-like individual morphing to an upright modern human is anything but accurate.


This work was performed by teams of scientists from around the world, including those in Australia, Germany, USA, Morocco, France, UK and Italy.

Anthro Wars / Will Earliest H. sapiens please stand up?

Reconstruction 300,000 y.o. Jebel Irhoud by John Bavarro

reconstruction by Kennis & Kennis

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A post on Dienike’s Anthropology Blog from 2011, before Jebel Irhoud site in  Morocco was reopened and new fossils identified as earliest Homo sapiens (to date) were dated to 300,000 y.a. 

http://dienekes.blogspot.com/2011/05/is-jebel-irhoud-father-of-mankind.html

May 20, 2011

Is Jebel Irhoud the Father of mankind?

The redating of the human Y-chromosome phylogeny to about 142 thousand years ago and the relocation of its most ancient lineages from east and south Africa to the Northwest marks a watershed moment in our understanding of human prehistory.

It is a fortuitous coincidence that there actually is a sample of humans from Northwest Africa from around the same time: Jebel Irhoud, about 160 thousand years ago from Morocco:

Jebel Irhoud is a cave site located about 100 km west of Marrakech, Morocco. The site is known for the numerous hominid fossils discovered there. Currently, the site has yielded seven specimens. The best known of these are portions of two adult skulls, Irhoud 1 and 2, a child’s mandible (Irhoud 3), and a child’s humerus (Irhoud 4). Fossils 1-3 were discovered while the cave was being quarried for barytes and thus their exact context and age has been subject to debate. Originally the Irhoud hominids were considered North African Neandertals. It is now clear that they are best grouped with other early anatomically modern humans such as Qafzeh (Israel) and Skhul (Israel).

A 2007 article by Smith et al. is extremely important for this population: (of course, other Anthropologists disagree) 

Earliest evidence of modern human life history in North African early Homo sapiens

Tanya M. Smith et al.

Recent developmental studies demonstrate that early fossil hominins possessed shorter growth periods than living humans, implying disparate life histories. Analyses of incremental features in teeth provide an accurate means of assessing the age at death of developing dentitions, facilitating direct comparisons with fossil and modern humans.

It is currently unknown when and where the prolonged modern human developmental condition originated. Here, an application of x-ray synchrotron microtomography reveals that an early Homo sapiens juvenile from Morocco dated at 160,000 years before present displays an equivalent degree of tooth development to modern European children at the same age. Crown formation times in the juvenile’s macrodont dentition are higher than modern human mean values, whereas root development is accelerated relative to modern humans but is less than living apes and some fossil hominins. The juvenile from Jebel Irhoud is currently the oldest-known member of Homo with a developmental pattern (degree of eruption, developmental stage, and crown formation time) that ismore similar to modern H. sapiens than to earlier members of Homo. This study also underscores the continuing importance of North Africa for understanding the origins of human anatomical and behavioral modernity. Corresponding biological and cultural changes may have appeared relatively late in the course of human evolution.

In the recent paper on the Ceprano calvarium, Irhoud 1 clearly belonged in the modern human cluster, and so it was in my re-analysis of that data, as were skulls from the Sudan and Tanzania in Africa, and the Qafzeh/Skhul early skulls from the Levant.

It thus seems to me, that the earliest modern human skulls are found in North/East Africa and West Asia, while the root of the Y-chromosome phylogeny is provisionally in Northwest Africa and seems to be in agreement with the autosomal evidence for a bottleneck in the human population at around 150,000 years ago.
Here is the interesting part: Irhoud had been once seen as a Neandertal. Indeed, it displayed some Neandertal-like leanings in a previous analysis. The consensus now (supported by the results of Mounier et al.) seems to be that it was modern human, but the Neandertal connection does not stop there:
The lithic industries of Jebel Irhoud were Mousterian, the same as Neandertals.Mousterian industries link European Neandertals, with modern humans in North Africa and the Near East. The Mousterian industries represented a genuine progress over the Acheulean tools that archaic humans had been using for hundreds of thousands of years before, and they, in turn, were replaced by the Aurignacian at exactly the time that Cruciani et al. date the main Y-chromosome CT clade that encompasses all Eurasians and most Africans.
The evidence seems to be in astonishing agreement with my hypothesis about the so-called “Neandertal admixture” in modern humans:
  • Early modern humans originated in North Africa, or at least somewhere between North and East Africa. Their traces may very well be hidden under the sands of the once (or thrice) green Sahara
  • They formed a clade with Neandertals, and used the same Mousterian tools, while humans elsewhere continued to use the older Acheulean ones. Both of them could very well have descended from Homoheidelbergensis, although the transition is not yet clear.
  • They expanded briefly into West Asia after Marine Isotope Stage 5, 120,000 years or so ago, and appeared in the Levant (Skhul/Qafzeh). As the Sahara dried up, they must’ve spread both to West Asia, and deeper into Africa, and, not surprisingly, the next major branching of the Y-chromosome phylogeny dates to about that time; this accounts for the deep (but not deepest) Y-chromosome lineages in modern day San.
  • Eventually (around 40,000 years ago, after the end of wet Marine Isotope Stage 3), they developed the even more advanced Aurignacian technology, and went on to conquer most of the world, driving the Neandertals to extinction. As the Sahara dried up, they expanded into Sub-Saharan Africa once again, and this time they inundated it with their genes.

Hence, the Modern-Neandertal affinity is not the result of any hypothetical admixture event between the two: Sub-Saharan Africans have also preserved some of the genetic legacy of the older Acheulean-using populations of the continent which shifts them somewhat away from other modern humans and Neandertals.

see original for more…

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A photo identified by John Hawks (2017 tweet) as Jebel Irhoud Homo sapiens left, (assume it’s the “new” 300 K model) and La Ferrassie Neanderthal (50-70,000 K)

La Ferrassie 1 Neanderthal (approx. date 50-70,000 y.a.)

Below: A Jebel Irhoud skull identified (Smithsonian) as 160,000 y.o. Homo sapiens. Ryan Somma.

Above: (see abstract below) 300,000 y.o. Jebel Irhoud composite: Philipp Gunz/MPI EVA Leipzig Image caption: A reconstruction of the earliest known Homo sapiens skull based on scans of multiple original fossils (this is not a complete skull from an individual)

And, let’s not forget: A Homo erectus reconstruction. (there are many…)

Confused yet?

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Abstract of paper introducing new Jebel Irhoud fossil finds and 300,000 y.a. date

New fossils from Jebel Irhoud, Morocco and the pan-African origin of Homo sapien

Jean-Jacques Hublin (see original for authors)

Nature volume 546, pages 289–292 (08 June 2017) doi:10.1038/nature22336

Fossil evidence points to an African origin of Homo sapiens from a group called either H. heidelbergensis or H. rhodesiensis. However, the exact place and time of emergence of H. sapiens remain obscure because the fossil record is scarce and the chronological age of many key specimens remains uncertain. In particular, it is unclear whether the present day ‘modern’ morphology rapidly emerged approximately 200 thousand years ago (ka) among earlier representatives of H. sapiens1 or evolved gradually over the last 400 thousand years2. Here we report newly discovered human fossils from Jebel Irhoud, Morocco, and interpret the affinities of the hominins from this site with other archaic and recent human groups. We identified a mosaic of features including facial, mandibular and dental morphology that aligns the Jebel Irhoud material with early or recent anatomically modern humans and more primitive neurocranial and endocranial morphology. In combination with an age of 315 ± 34 thousand years (as determined by thermoluminescence dating)3, this evidence makes Jebel Irhoud the oldest and richest African Middle Stone Age hominin site that documents early stages of the H. sapiens clade in which key features of modern morphology were established. Furthermore, it shows that the evolutionary processes behind the emergence of H. sapiens involved the whole African continent.

More to come…

 

Neanderthal Cave Art? / Anthropology Wars

Why is it that in any anthropologic scenario, one group must win and “the other” group must become extinct? There is a difference between one community of people (let’s say the Roanoke Colony), failing to thrive, and this “failure” being proof that all English people became extinct.  We project the “winner versus looser” plot onto evolutionary history, that as yet, we do not understand. 

Video from the scientific article “U-Th dating of carbonate crusts reveals Neanderthal origin of Iberian cave art” (www.sciencemag.org)

One comment: It continues to baffle the logical Asperger, as to why neurotypicals insist that any intentional mark on a rock, or any other object, is automatically “symbolic” expression and “proves” abstract thought in the brain of the “mark maker” when a drawing can be (and usually is) concrete and literal: the drawing of a cave lion is a lion. The arrangement of lines in a drawing into which animals are being driven, is a corral; the animals are specific animals. “Bad” prehistoric drawings (inept person attempting to draw an object) are not 20th C. abstract art!

John Hawks on evidence of Neanderthal / H. sapiens occupation and cultural sharing  in the Carmel area of northern Israel.

The always sane and rational John Hawks…

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And for two other narratives, go to: 

http://discovermagazine.com/2016/june/15-when-neanderthals-replaced-us

https://www.smithsonianmag.com/science-nature/were-neanderthals-earliest-cave-artists-new-research-spain-points-possibility-180968236/

 

The Incredible Shrinking Neurotypical Brain / Updated

The PRIMARY problem with all this mad calculation of brain-body-species variables is a big conceptual mirage that modern social Homo sapiens are magically endowed with Supreme Intelligence, while 1. ignoring the intelligences of other life forms and 2. utterly ignoring the real world consequences of our impulsive rush to interfere with all things natural, but  without a single thought to the consequences of disrupting a planetary system of matter-energy transformations that have been driving change and abundant evolution of forms for 3.5 BILLION years. Stupid big brain? Could be.

What about evaluating “brains” (or other sensory-regulatory systems) across the entire catalog of life forms for effective and productive adaptation to the environment; a RESULTS based analysis, requiring an end to obsessive anthropomorphic novel-writing. Extinction cannot be a factor in this analysis, because 99% of all species are extinct. Try proving the human conceit that all these species became extinct because of “small brain syndrome”! The fact that H. sapiens, Master Species of the Universe, exists today, (last Homo Standing self-awarded trophy) has no meaning in terms of evolution as an ongoing process. It is a safe bet that we too, will soon be “out of evolutionary fashion” as we hurry to increase climate changes and challenges to our survival.

The process of evolution takes place in the present: it is not run by a “conscious entity” that “invents” a time regime of Past / Present / Future. 

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Two videos about a “taboo” subject; one trend in brain size is ignored by contemporary white male cheerleaders who insist on the evolutionary supremacy of modern social humans: the incredible shrinking post-agricultural social brain. The two videos vary somewhat, but both introduce an idea that I’ve been stressing over and over in blog posts – a less intelligent modern brain; the result of the dumbing down due to neoteny-domestication that has taken place in Homo sapiens since the agriculture-urbanization lifestyle change. One of the consequences of living in manmade environments has (likely) been the atrophy of visual perception and processing in the social brain and the lack of development into full adulthood, resulting in a “default setting” of magical thinking, which is a stage in childhood development that appears to have become “permanent” in modern social humans – Neurotypicals. An imaginary supernatural domain is believed to “control” human lives and physical reality, in spite of overwhelming evidence to the contrary.

John Hawks – a thoroughly credible anthropologist (as far as that goes: I’m not an anthropologist). Note the brain size comparison: Neanderthal < Ancient Homo sapiens > Post agricultural Modern Homo sapiens.

Another familiar theme: that meat eating caused the current decline and that “being vegan” is necessary to reversing it, is contrary to evolution history(Plus we also have claims for the “Paleo Caveman Diet) but “crappy food” supplanting healthy food is accelerating  the situation. It was the advent of meat eating that allowed for an increase in brain size: our energy-sucking brain uses 20% of the energy we generate and must have protein and fat to survive. (A “big brain” is no asset if you can’t feed it and it doesn’t provide a big advantage in cultural adaptation) Herbivores convert a much lower percentage of energy from their food than do carnivores.

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I’m not claiming that Asperger types have larger brains, but that we retain pre-domestication brain organization (mainly reliance on visual perception and processing, direct sensory information gathering and attention to the nonhuman environment) that have “survived” the selection for juvenile traits that  produced modern social humans.

More from John Hawks Blog / 

Human brain evolution looks gradual. If you ignore enough data…

Bernard Wood’s research group has a new paper on brain size evolution in hominins, led by Andrew Du in Proceedings of the Royal Society, Series B: “Pattern and process in hominin brain size evolution are scale-dependent”.

In this paper, I notice that the researchers have done a really weird thing: Their analyses include only hominin fossils before 500,000 years ago.

Here’s their main figure:

Figure 2 from Du and colleagues showing endocranial volumes of hominin fossils over time
Figure 2 from Du and colleagues (2018).

Each of the symbols in this figure represents a single fossil hominin specimen that has an estimate of endocranial volume. The specimens reflect every hominin species from Australopithecus afarensis up to “Homo heidelbergensis”. Modern humans and Neanderthals have been left out of the dataset—they don’t fall within the pre-500,000-year time range.

On the basis of this dataset, the authors conclude that the entire hominin lineage is compatible with a single pattern of gradual evolutionary increase over time:

Figure 3b from Du and colleagues showing the data fitting a gradual model of brain size increase over time
Figure 3b from Du and colleagues (2018). Each point here is the data average in each 200,000-year-long interval, connected by a line. The shaded area indicates a range consistent with gradual linear increase over time. The mean for each time interval of 200,000 years is plotted here, and none of the means fall outside the predicted error range for a gradual linear increase.

So what’s weird about this?

Let’s look at what the data show if we don’t impose an artificial limit of 500,000 years ago:

Same figure as above with hominin endocranial volume data, but this time with Homo naledi and Homo floresiensis added
Same figure as above, but this time with Homo naledi and Homo floresiensis added.

Hey, look at that! There are two species entirely missing from the data examined by Du and colleagues. The fossil records of endocranial volume in Homo naledi and Homo floresiensis both date to the last 300,000 years. When you include them, they both reject the notion of gradual monotonic increase in brain size.

It is likely that Homo naledi branched from the lineage of Neanderthals and modern humans more than a million years ago, maybe much longer. In other words, H. naledi ancestors must have existed throughout much of the last phase of our evolutionary history, and we haven’t found them yet. The same is true of H. floresiensis—and I don’t assume that Flores is the only place where such a population may have existed. The real message of these species is that the Lower and Middle Pleistocene records must undersample hominin diversity.

In neither case is it clear whether the small brains of these hominins resulted from a reversal from a larger-brained ancestor, or whether their small brain size was retained from the common ancestor of Homo.

The paper doesn’t justify its exclusion of this key evidence, so I don’t really know why the authors chose to ignore the data. There are other strange decisions underlying the analyses here—including the strange assumption that a gradual monotonic increase is an appropriate model across many species that are not a single ancestor-descendant lineage. I think that what looks like a “fit” is actually just an illustration of how weak the data are.

What’s obvious that the conclusions would be different if all the evidence were included.