New Fossil May Trim Branches of Human Evolution

Becky Nitschelm
October 20, 2013
P2
Mr. Mathieu

Science Friday
Host: John Dankosky
Produced by: Alexa Lim, Associate Producer
Guest Speaker: Adam Van Arsdale, Assistant Professor Anthropology Wellesley College
Published: October 18, 2013

Listen to It: http://www.sciencefriday.com/playlist/#play/segment/9250 

Summary: Many scientists believe that homo sapiens (humans) come from many different species including homo habilis (from 2.3 million years ago) and homo erectus (from 1.8 million years ago). However, a skull discovered in Dmanisi, Georgia from about 1.8 million years ago,under the site of an old medieval structure from about 1000 years ago, suggests otherwise. Many fossils of homos have been found at this site. One of them, skull 5, is know as the best preserved skull ever found older than 100,000 years old. From the fossils found at the site, scientists get a complete view of what homos were like 1.8 million years ago. The individuals found are both male, female, old, and young and are from the same time period. Each individual has variations between them, similar to the differences that can be seen today in modern chimpanzees or humans. Previous fossils found about human evolution come from sites in East Africa. These fossils show wide ranges of variation over large periods of time (some fossils differ in age up to 400,000 years). From these, scientists concluded that this large amount of differences between homos can only be because they are from different species. However, the fossils at Dmanisi, including the recently discovered skull 5, which rounds out the picture, show that there can be these large differences between homos in the same species. This variation could just be a result of variation due to evolution, or changes that occur over time. This suggests that the homo genus is all from a common ancestor; it is one continuous line of evolution that does not branch out into different species. Adam Van Arsdale, professor at Wellesley College, believes that this conclusion about evolution of homo sapiens is true and that the genus homo developed due to an increasing niche for humans (new tools and places to live). This new niche makes it harder for a new species to branch out, giving more evidence to the conclusion.

Connection: This connects to what we have been learning in many ways.  We also spent time on niches of animals and how that effects them. In this article, Van Arsdale believes that the increasing niche of humans due to new tools and new environments created the genus homo. Also, he thinks that this niche causes less of a chance of a new species to arise. This relates to our study of niches and how if two species occupy the same niche, then one may be hurt by the other (competitive exclusion). In addition, we learned about the evolution of species. We learned that species have to adapt to changes around them in order to survive. This is what is known as evolution, or change over time. In this article, it talks about the evolution of the homo genus and the human species. Also, we learned about biodiversity, which is the differences of life on Earth. I think this relates slightly to this article because in this article in shows the diversity between a single species.