Class Notes (807,339)
Canada (492,708)
Biology (2,348)
BIOLOGY 1M03 (663)
Ben Evans (167)
Lecture 18

BIOLOGY 1M03 Lecture 18: 18- Hominin Evolution, Neanderthal Genome, Denisova Genome and Gene Flow

5 Pages
Unlock Document

McMaster University
Ben Evans

Bio 1M03 February 22, 2016 Hominin Evolution, Neanderthal Genome, Denisova Genome and Gene Flow Out of Africa/ Complete Replacement Hypothesis - Proposes that modern humans dispersed out of Africa and replaced populations of H. erectus and Neanderthals without interbreeding Multiregional evolution - Proposes that evolution of modern humans has been occurring since early humans (H. erectus) left Africa 2 mullion years ago - Continuous exchange of genes among population in different regions united this species as it evolved into modern humans - Supported by primitive characteristics in some modern races o Shovel shaped incisors in Asians o Prognathic face and large cheeks in Australian aboriginals - But these features could be convergently evolved, or simply a polymorphic ancestral feature Timing of Recent Hominin Fossils Neanderthals Origin - Present in western Eurasia from approximately 127,000 years ago – 30,000 years ago - But probably as far back as 400,000 years ago - Lived in Europe, Western Asia and Southern Siberia - Anatomically modern humans were living in these areas at this time from approximately 80,000 years ago - Faces that bulge in the middle - Large brow ridges - Rounded back of the skull - Large cranial capacity around 1,400 cc, larger than modern humans - Robust - Heavily muscled bodies - More stocky than modern humans - Morphology may reflect adaptation to cold Neanderthal Culture - Mode 3 tool industry - Mostly meat eaters but evidence of plant material has also been recovered on fossil molars - Probably wore clothes, evidence of bones sewing needles and awls - Controlled fire also made symbolic or ornamental objects - Deliberated burial of dead and potentially marking of graves with flowers Neanderthal Extinction - Maybe H. sapiens could have been involved with violent conflict and replacement of H. neanderthalensis - Maybe hybridization led to fusion of H. sapiens and H. neanderthalensis - Maybe climate changes or energetic requirements made H. neanderthalensis unfit Homo florensis - Only about 3 feet tall - Very small brains, around 380 cc, similar to chimps - Lived between 35,000 and 14,000 years ago - Island of Flores in Indonesia - Some researchers think these were descendants of H. erectus that became isolated and evolved different characteristics because of natural selection - Island dwarfism - Alternatively these individuals made up a modern human population with a small stature and microcephaly - But this is not supported by recent analyses - Attempts to extract DNA from H. florensis were unsuccessful - Lack of success is most likely due to environmental conditions being bad for long term DNA preservation What can we learn from Genetic Analyses? - Genetic data from extant samples - Genetic data from extinct samples - Information from different genomic regions (mitochondrial DNA, autosomal DNA) Human mtDNA - Variation within African populations is as great as that between Africa and other populations or between other populations - Greatest divergence between non-African haplotypes corresponds to times between 90,000-180,000 years - This implies that early Asian Homo (H. erectus, H. florensis) did not contribute mtDNA that survives in modern humans - Intra-species divergence times of some parts of the human genome are very ancient (2 million years old) - One way that this could happen if there was population structures in Africa before AMH left Africa - Another way that this could happen if there was gene flow with another diverged hominin Where did the DNA for the Neanderthal Genome Project come from? - DNA was extracted from three bones from different individuals - One was date ~38,000 years ago, another to ~45,400 years ago and the third was undated What can we compare the Neanderthal Genome to? - The project also generated whole genome data from 5 human populations and also compared Neanderthal genome to a previously available genome sequence of chimpanzees Did we reproduce with Neanderthals? - The data from Neanderthals allowed scientists to test whether there was evidence for gene flow between modern humans and Neanderthals - They did this by quantifying how similar the Neanderthals genomes were to other modern human genomes from Africa, Europe, Asia and
More Less

Related notes for BIOLOGY 1M03

Log In


Don't have an account?

Join OneClass

Access over 10 million pages of study
documents for 1.3 million courses.

Sign up

Join to view


By registering, I agree to the Terms and Privacy Policies
Already have an account?
Just a few more details

So we can recommend you notes for your school.

Reset Password

Please enter below the email address you registered with and we will send you a link to reset your password.

Add your courses

Get notes from the top students in your class.