Our Neandertal Brethren: Why They Were Not a Separate Species

According to the late Harvard University biologist Ernst W. Mayr, the greatest evolutionary theorist since Charles Darwin, “species are groups of actually or potentially interbreeding natural populations which are reproductively isolated from other such groups.”

Reproductive isolation is the key to understanding how new species form, and many types of barriers can divide a population and split it into two different groups: geographic (such as a mountain range, desert, ocean or river), morphological (a change in coloration, body type or reproductive organs), behavioral (a change in breeding season, mating calls or courtship actions), and others. After isolation, if members of the split populations encounter one another and cannot produce viable offspring that can themselves later successfully interbreed and produce viable offspring (hybrids such as mules are infertile), then these two populations constitute two different species.

Let’s say that a species migrates out of Africa into Europe around 400,000 years ago and becomes reproductively isolated from its ancestral population for the next 320,000 years. It evolves distinctive anatomical features and adaptations for the colder climes. Moreover, even after other descendants of the original ancestral population move into Europe around 80,000 years ago, the skeletons from both groups show no obvious signs of blended characteristics. Modern scientists classify the creatures as two different species.

Then, however, genetic analysis reveals that members of these two species interbred and produced viable offspring that populated Europe and spread eastward as far as China and Papua New Guinea. By Mayr’s definition, these two interbreeding populations are not two species after all, but two sibling subspecies of the original African species. A subspecies has a characteristic appearance and geographic range, Mayr explains, yet he adds this significant qualifier: “It is a unit of convenience for the taxonomist, but not a unit of evolution.”

Thus it is—revealing the identity of my example—that we must reclassify Homo neanderthalensis as Homo sapiens neanderthalensis, a subspecies of Homo sapiens. A comprehensive and technically sophisticated study published in the May 7 issue of Science, “A Draft Sequence of the Neandertal Genome,” by Max Planck Institute evolutionary anthropologists Richard E. Green, Svante Pääbo and 54 of their colleagues, demonstrates that “between 1 and 4% of the ge nomes of people in Eurasia are derived from Neandertals” and that “Neandertals are on average closer to individuals in Eurasia than to individuals in Africa.” In fact, the authors note, “a striking observation is that Neandertals are as closely related to a Chinese and Papuan individual as to a French individual.... Thus, the gene flow between Neandertals and modern humans that we detect most likely occurred before the divergence of Europeans, East Asians, and Papuans.” In other words, our anatomically hirsute cousins are actually our genetic brothers.

Read the Article

Laurie Santos: A monkey economy as irrational as ours

Laurie Santos looks for the roots of human irrationality by watching the way our primate relatives make decisions. A clever series of experiments in "monkeynomics" shows that some of the silly choices we make, monkeys make too.

About Laurie Santos
Laurie Santos studies primate psychology and monkeynomics -- testing problems in human psychology on primates, who (not so surprisingly) have many of the same predictable irrationalities we do.

Selective creationists

Some interesting, if terrifying statistics from the Why Evolution Is True website.


This flashy graph has already been posted on Pharyngula, but I thought I’d echo P. Z.’s sentiments. This graph comes from a survey of high school biology teachers published in PLoS Biology in 2008 (download is free). The teachers were asked about their personal beliefs about human origins (click to enlarge):


Only a tad more than one in four teachers really accepts evolution as scientists conceive of it: a naturalistic process undirected by divine beings. Nearly one in two teachers thinks that humans evolved but that God guided the process.

Can we count those 48% of “guided-by-Godders” 0n our side? I agree with P. Z.: the answer is NO. Yes, they do accept that our species changed genetically over time, but they see God as having pulled the strings. That’s not the way evolution works. The graph labels these 48% as believers in intelligent design, and that’s exactly what they are, for they see God as nudging human evolution toward some preconceived goal. We’re designed. These people are creationists: selective creationists.

Read the Article

Chew on this: thank cooking for your big brain

THE French have elevated it to an art form, and even the British have got better at it - but chimps can't cook at all. According to one controversial evolutionary theory, early humans developed a taste for cooked food around 2 million years ago, and this set in motion a series of changes that made us utterly different from any other animal.

Now the proponents of the cooked-food hypothesis are presenting fresh evidence in support of the idea - and it all comes down to how you chew.

The theory, championed by Richard Wrangham at Harvard University, has divided palaeoanthropologists. In an attempt to convince the doubters, Wrangham and his colleagues have been amassing empirical evidence, including evolutionary adaptations consistent with a diet of heated food, such as the small size of our guts.

At the Evolution 2010 conference in Portland, Oregon, at the end of June, Christopher Organ of Harvard and Brown University in Providence, Rhode Island, presented what he and Wrangham say is the best evidence yet that we are adapted to eating cooked food, and that this is the result of events that occurred early on in human evolution.

Read the Article

Fossil links humans and monkeys

Researchers have discovered the skull of a 29 million-year-old animal that could be a common ancestor of Old World monkeys and apes, including humans.

It indicates that apes and Old World monkeys diverged millions of years later than previously thought, say the scientists.

The discovery was made in Saudi Arabia by researchers from the University of Michigan.

They described the primate, Saadanius hijazensis, in the journal Nature.

Dr William Sanders from the University of Michigan, who led the research, said this was "an extraordinary find".

The skull of this previously unknown species had some features that are shared by Old World monkeys and apes, including humans, today.

Read the Article

BBC: Humans' early arrival in Britain

Researchers have discovered stone tools in Norfolk, UK, that suggest that early humans arrived in Britain nearly a million years ago - or even earlier.

The find, published in the journal Nature, pushes back the arrival of the first humans in what is now the UK by several hundred thousand years.

Environmental data suggests that temperatures were relatively cool.

This raises the possibility that these early Britons may have been among the first humans to use fire to keep warm.

They may also have been some of the earliest humans to wear fur clothing.

Read the Article

Bonobos have a secret

In the 1920s Robert Yerkes acquired an unusual ape that he named Prince Chim. Chim was more intelligent, fun-loving, cooperative, emotionally positive and full of life than his chimpanzee companion, Panzee. Chim's vocal behaviour was so prolific and reminiscent of language that Yerkes transcribed it using musical notation. Yerkes had discovered the bonobo.

In the 80s and 90s researchers conducted a study comparing a chimp and a bonobo. The aim was to determine if Yerkes's observations were accurate and if either animal, or both, could learn a human language through cultural immersion rather than instruction. The answer for both apes was yes.

Vanessa Woods writes engagingly of her husband, primatologist Brian Hare, struggling to tackle these questions again. Seemingly ignorant of the earlier work, in 2005 Hare embarked on a mission to find out what differentiates bonobos from chimps. With the Democratic Republic of Congo still mired in the aftermath of war, he travelled to the Lola Ya sanctuary in Kinshasa to study bonobos.

Hare found that bonobos do all kinds of things that chimps are not reported to do: they experience constant genital arousal, become attached to individual humans, think up new ways to engage in sexual, altruistic or cooperative behaviour on an essentially non-stop basis, and they die of broken hearts. In short they are a lot like people, even uncomfortably so - a fact that, ironically, has caused many scientists to ignore them.

Read the Article

Can Monkeys Talk?

Robert Seyfarth describes how monkey calls used by Vervet Monkeys might be precursors to language.

To read more about language in monkeys (and chimps), see the NY Times article: "Deciphering the chatter of monkeys and chimps"