Vertebrate mammals Flashcards

Question

What was different about the teeth of the Ardipithecus?

Answer 1

- Reduced canines - Males and females have similar detention - Enamel thicker, indicative of switch away from fruit towards more abrasive terrestrial foods

Answer 2

- It did not knuckle walk and lacked all of the specializations needed to avoid injuries in arboreal life - Wrist and finger joints were more flexible than those of apes - Midcarpal joint in wrist was very flexible - Suggests that hand form has changed more dramatically in ape lineage

Answer 3

They had a mosaic pelvis - Changes in upper pelvis indicated that walked upright on ground - Gluteal muscles repositioned so could walk without moving from side-to-side - Lower pelvis was ape-like and so probably maintained capacity to climb

Answer 4

- Modern apes have a highly flexible midfoot for grasping and vertical climbing - Ardipithecus still has opposable big toe for grasping - Ardipithecus possesses a foot bone (os peroneum) that keeps the foot rigid

Answer 5

It suggests that our last common ancestor was ape-like, had short back, arms for swing, and pelvis and limbs for knuckle-walking - Chimps and apes kept these features while our ancestors lost these traits - Scientists surprised that Ardipithecus was strikingly different to our primate relatives - Ardipithecus represents a new type of hominin that is neither ape or human like - Suggests that our common ancestor never knuckle-walked - Suggests that it might be apes that have evolved most from the last common ancestor

Answer 6

Also known as the Upright Man, they were the first hominin to migrate out of Africa, colonizing Europe and Asia (Java man) - Lived from ~1.9 to 0.1 MYA - Had human-like body proportions: - Larger brain - Same sexual size dimorphism as modern humans - Bipedal bone structure

Answer 7

- All homo sapiens evolved from a second major migration out of Africa ~100 MYA - Migrants completely replaced all regional populations derived from first H. erectus migrations (1-2 mya) Evidence - High genetic similar between ethnic groups suggests recent origin and small founding population

Answer 8

- Neanderthals present in Europe from 600,000 to 40,000 YA - Coexisted with Homo sapiens 30-40,000 YA - Neanderthals had brains as large as ours, though somewhat different in shape - They buried their dead - Neanderthals were generally more heavily built than modern humans

Answer 9

Sequence analysis of ancient DNA samples and their comparison with those of extant species - Ancient DNA is highly fragmented - Microbial contamination - Recent innovations in sequencing technology perform well with such short fragments

Answer 10

Neanderthal mtDNA falls outside the variation of extant human mtDNA variation - Mean divergence time between Neanderthal and extant human mtDNAs of 660,000 years - Chimps and hominins diverged 6-8 MYA

Answer 11

Yes, - Europeans and Asians share 1-4% of their nuclear DNA with Neanderthals - Strikingly, 50% of our human leukocyte antigen (HLA) genes, come from Neanderthals, have an important role in our immune response - Africans do not share DNA with Neanderthals

Answer 12

- Important information on how the world was populated at the time when Homo sapiens migrated out of Africa and spread to the rest of the world - Neanderthals lived in the west and Denisovans in the east on the Eurasian continent - Interbreeding occurred when Homo sapiens spread across the continent, leaving traces that remain in our DNA

Answer 13

The use of molecular tools (protein and DNA sequences) to determine the evolutionary links between ancient and modern hominids - The protein evolution hypothesis proposes that changes in the coding region of genes resulted in important modifications - Gene regulatory evolution hypothesis proposes that differences between chimps and humans due to patterns of turning on and off of genes - The less-is-more hypothesis proposes that man has lost many ape-like traits (body hair, muscle mass) through loss-of-function mutations

Answer 14

The 'language' gene - FOXP2 (Forkhead box P2) is thought to play a role in human language - Mutations in gene linked to speech impediments - Mutations linked to reduced activity in Broca's area of brain - Gene sequence is very well conserved across mammals but 2 amino-acid substitutions in humans - FOXP2 is a transcription factor and so fits the gene regulatory evolution theory - Mice carry 'humanized' FOXP2 gene solve mazes better

Answer 15

DUF1220 (unknown function) is expressed at high levels in the brain regions associated with higher cognitive function (neocortex)

Answer 16

Searched for differences in gene expression between brains of humans, chimps, orangutan, and monkeys - Found that transcription factors are more abundant in human liver, consistent with the theory of gene regulatory evolution

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Vertebrate mammals Flashcards

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