Natural Selection and the Human Skull

Mar 18, 2008

New research led by UC Davis anthropologist Tim Weaver adds to the evidence that chance, rather than natural selection, best explains why the skulls of modern humans and ancient Neanderthals evolved differently. The findings may alter how anthropologists think about human evolution.

Weaver's study appears in the March 17 issue of the Proceedings of the National Academy of Sciences.

It builds on findings from a study he and his colleagues published last year in the Journal of Human Evolution, in which the team compared cranial measurements of 2,524 modern human skulls and 20 Neanderthal specimens.

Natural Selection and the Human Skull
The approximate locations of the cranial measurements used in the analyses are superimposed as red lines on lateral (A), anterior (B), and inferior (C) views of a human cranium. (National Academy of Sciences, PNAS (Copyright 2008))

The researchers concluded that random genetic change, or genetic drift, most likely account for the cranial differences.

In their new study, Weaver and his colleagues crunched their fossil data using sophisticated mathematical models -- and calculated that Neanderthals and modern humans split about 370,000 years ago. The estimate is very close to estimates derived by other researchers who have dated the split based on clues from ancient Neanderthal and modern-day human DNA sequences.

The close correlation of the two estimates -- one based on studying bones, one based on studying genes -- demonstrates that the fossil record and analyses of DNA sequences give a consistent picture of human evolution during this time period.

"A take-home message may be that we should reconsider the idea that all morphological (physical) changes are due to natural selection, and instead consider that some of them may be due to genetic drift," Weaver said. "This may have interesting implications for our understanding of human evolution."

Weaver conducted the research with Charles Roseman, an anthropologist at the University of Illinois at Urbana-Champaign, and Chris Stringer, a paleontologist at the Natural History Museum in London.

Source: UC Davis

Explore further: New genetic 'operating system' facilitated evolution of 'bilateral' animals

add to favorites email to friend print save as pdf

Related Stories

Study shows how chimpanzees share skills

3 hours ago

Evidence of new behaviour being adopted and transmitted socially from one individual to another within a wild chimpanzee community is publishing on September 30 in the open access journal PLOS Biology. This i ...

Rating the planet's oceans

2 hours ago

The most comprehensive assessment conducted by the Ocean Health Index rates the Earth's oceans at 67 out of 100 in overall health. In addition, for the first time, the report assessed the Antarctic and the ...

Group: Wildlife populations down drastically

23 hours ago

Populations of about 3,000 species of wildlife around the world have plummeted far worse than previously thought, according to a new study by one of the world's biggest environmental groups.

Recommended for you

World's first microbe 'zoo' opens in Amsterdam

5 hours ago

The world's first "interactive microbe zoo" opened in Amsterdam on Tuesday, shining new light on the tiny creatures that make up two-thirds of all living matter and are vital for our planet's future.

User comments : 1

Adjust slider to filter visible comments by rank

Display comments: newest first

AJW
1 / 5 (1) Mar 19, 2008
Natural selection does produce "all"
change. The "genetic drift" defines
natual selection precision or said
another way, 'It is the measure of
environmental tolerance.'