Human Evolution http://www.pbs.org/wgbh/evolution/library/07/1/l_071_01.html

Topics covered in slide show Two theories on how evolution occurs Phylogeny and Cladograms Fossil Record and its gaps Human Evolution as determined from fossil record Are we still evolving?

Types of Evolution Gradualism Punctuated Equilibrium Both play a role in evolution

Gradualism Most evolutionary changes occur over long periods of time (when enviro. Is changing slowly)

Punctuated Equilibrium Major evolutionary changes happen relatively rapidly and then are followed by a long period of very little change (occurs when species are exposed to new or rapidly changing enviro.)

Phylogeny and Cladograms Phylogeny -Evolutionary relationship between organisms Cladograms -Diagram showing the evolutionary relationship of different groups of species

Cladogram

Evolution of Hominid Species

Fossil Record and its Gaps In evolution, one of the key sources of evidence in fossils There are gaps in fossil record Gaps don’t undermine all the other evidence of evolution Scientific investigations are continually filling these gaps

Human Evolution as determined from fossil record There is a rich fossil record of human ancestors Homo sapiens first evolved in Africa and began spreading our from Africa 50 000 years ago Key evolutionary characteristics of humans: Bipedalism Large brain Fine manipulation with hands

Migration of Early Hominids

Continued… Humans closest related living species is the chimpanzee (closest relative)

Are we still evolving? Rate of human evolution has been greater over the past several thousand years than during the past few million years Eg. Evolution of lactose tolerance Evolution of infectious diseases (HIV) and human’s evolutionary responses are being studied Artificial selection of plants and animals has caused human population to explode

Continued Understanding our evolutionary past has many benefits In the past, taste for sweets and fats were beneficial Darwinian medicine (use of evolutionary theory to understand medicine) is insightful into cause and spread of disease

Continued We have evolved a brain capable of knowing how to obtain a sustainable future We have the tools and freedom to direct our unknown evolutionary future

Reference Biology 11 Nelson 2011

Questions Did we evolve from the chimpanzee? Justify your answer Trace the migration of homo sapiens. Does Cultural evolution affect biological evolution? Justify your answer.