MadSci Network: Evolution

Re: Are we being lied too?

Date: Fri Aug 1 02:21:46 2003
Posted By: Steve Mack, Post-doc/Fellow, Molecular and Cell Biology
Area of science: Evolution
ID: 1059229697.Ev

MODERATOR'S NOTE: It seems to me that the MadSci Evolution FAQ might also be useful in a more general way than Steve's references, which refer to your question more specifically.
I’m always glad to see healthy skepticism at work, but it is difficult to provide a substantive answer without knowing which books you have been reading, or what you are referring to when you say, “actual findings in the field” and “all the evidence.” However, I think I can provide a satisfactory answer to your questions.

To begin, I want to point out that the so-called Cro-Magnon people were not the first Europeans. The first European people were Neanderthals, a sister species (Homo neandertalensis) of our own species (Homo sapiens) that lived successfully in Europe (and elsewhere) for 200,000 years. Neanderthals seem to have gone extinct soon (10,000 years) after members of our own species (the so-called Cro-Magnon people) arrived in Europe 40,000 years ago.

In addition, it is unclear what you mean by “a sudden evolutionary change” having occurred prior to the emergence of Cro-Magnon man. Ultimately, evolutionary change is a change in gene frequencies in a population over time. So far, we can only infer genetic changes in ancient humans by studying their skeletal remains. Based on their skeletal remains, the Cro-Magnon people are considered to be “anatomically modern”, which means that they looked like we do today. This distinguishes them from so-called “archaic” species in the genus Homo, for example, Homo antecessor, Homo habilis and Homo erectus. The oldest known skeletal remains of anatomically modern people are approximately 160,000 years old. So, considering skeletal remains, there doesn’t seem to have been a major “evolutionary change” in our species in 160,000 years. Until DNA can be obtained from some of these ancient skeletal remains, this is all that we can really say about the suddenness (or the lack thereof) of evolutionary change in ancient members of our species. Ironically, it has been possible to obtain DNA from Neanderthal bones, and this material has made it clear that Neanderthals belong to a separate species.

What has been the subject of considerable debate is the observation that tangible evidence of “symbolic thought” (things like art, an advanced material culture, widespread trade and possibly religion) is found associated with anatomically modern humans after 40,000 years ago, while (until recently) no such evidence older than 50,000 years had been seen. As you suggest, this seems to indicate that “abstract thought” did not develop until 40,000 years ago.

However, recent archaeological findings have called this line of reasoning into question. In 2002, a report was published in Science describing the discovery of red ochre engraved with abstract crosshatchings, along with unmarked but flattened pieces of ochre, finely carved bone tools and fishing equipment, all found in the Blombos Cave in South Africa. These artifacts were dated to an age of 77,000 years, making them the oldest evidence of an advanced material culture found so far. In addition, the flattened pieces of ochre are believed to have been worn down through repeated grinding (a process through which modern ochre-using cultures make paint), and are thought to have been used as body adornments for symbolic communication. Similar artifacts of material culture (red ochre, bone tools, fishing equipment) and evidence of semi-permanent settlement have been found at other African sites (e.g., Klasies River and Katanda) dating from 90,000 to 110,000 years in age.

In 2003, a pair of reports were published in Nature describing three anatomically modern skulls found in the Herto area of Ethiopia. These skulls were dated to an age of 160,000 years, and represent the oldest remains of members of our species. They show evidence of having been subjected to "mortuary practices"; the flesh had been intentionally removed from two skulls, and they show signs of having been worn smooth by repeated handling. The third skull bears a pattern of parallel scratches that run the perimeter of the skull. No post-cranial remains were found with the skulls, which suggests that they were kept separately from the associated bodies. Similar mortuary practices are carried out by modern cultures.

So, it seems likely that “symbolic thought” has been part of the human condition since the earliest days of our species. The material culture characteristic of so-called Cro-Magnon peoples is not something that simply appeared 40,000 years ago, but rather developed as part of the culture of our species over the previous 120,000 years. Imagine looking into the past from a vantage point 40,000 years in our future. No computers are going to be found in the “fossil record” prior to the 20th century, but there are going to be lots of them during and after the 20th century. Computer technology has resulted in a radical cultural development for our species, but we have undergone no radical evolutionary developments. However, knowing our own history, we can see how the rapid expansion of computer technology follows logically from the last 7,000 years of cultural development. The same thing is likely to be true for the material culture of our ancient ancestors.

Even if this were not the case, I wouldn’t go so far as to characterize our ancestors as “naked apes” that were “sitting on their butts”. One of the common misconceptions that people have about evolutionary processes is that they are rapid and occur over short periods of time. In fact, evolution is an extremely slow process; some theorists suggest that the minimum unit of time that evolution should be thought to operate in is one million years. Thinking about evolution from this perspective, the degree of cultural development that our ancestors managed to accomplish in 120,000 years is astonishing, and the degree that we have accomplished in the last 40,000 years is staggering.

Finally, I want to suggest that the best way to get a handle on a scientific issue is to read the current primary literature. Science works through the interaction of skepticism, peer-review and reproducibility, and the best place to find this is in the literature. A book can be written by anyone, with the purpose of advancing any theory, without peer-review, and without having to be tested by repetition in the scientific community.

Some references

77,000 year old artifacts found in the South African Blombos Cave

Henshilwood CS, d'Errico F, Yates R, Jacobs Z, Tribolo C, Duller GA, Mercier N, Sealy JC, Valladas H, Watts I, Wintle AG. Emergence of modern human behavior: Middle Stone Age engravings from South Africa. Science 2002 Feb 15;295(5558):1278-80.

Grine FE, Henshilwood CS. Additional human remains from Blombos Cave, South Africa: (1999-2000 excavations). Journal of Human Evolution 2002 Mar;42(3):293-302.

160,000 year old skulls found in the Herto region of Ethiopia

White TD, Asfaw B, DeGusta D, Gilbert H, Richards GD, Suwa G, Howell FC. Pleistocene Homo sapiens from Middle Awash, Ethiopia. Nature 2003 Jun 12;423(6941):742-7.

Clark JD, Beyene Y, WoldeGabriel G, Hart WK, Renne PR, Gilbert H, Defleur A, Suwa G, Katoh S, Ludwig KR, Boisserie JR, Asfaw B, White TD. Stratigraphic, chronological and behavioural contexts of Pleistocene Homo sapiens from Middle Awash, Ethiopia. Nature 2003 Jun 12;423(6941):747-52.

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