Upload
voquynh
View
216
Download
0
Embed Size (px)
Citation preview
BIOL 1010 Introduction to Biology: The
Evolution and Diversity of Life. Spring 2011
Sections A & BSteve Thompson: [email protected]
http://www.bioinfo4u.net1
Sunday, January 30, 2011
Human evolution — where we came from
Starting after the K-T boundary with the “Age of Mammals.” But mammals actually began much earlier, as we’ve seen . . .Remember the Therapsid Cynodonts during the Permian from last time.
2Sunday, January 30, 2011
The Cenozoic Era, Tertiary Period (65-1.8 MYA)
Huge adaptive radiation of mammals . . .Including most of the placental mammals, and the lineage leading to human beings, which began about 60 MYA. For example the “Ida” fossil . . .See http://www.revealingthelink.com/.Geological changes triggered huge climate changes, which molded species turnover. 3
Sunday, January 30, 2011
Plate tectonic events created
the present continents.
About 12 MYA India slammed into Asia creating the Himalayas.This produced a massive cooling effect that reduced the size of tropical forests across all of the ‘old world.’
4Sunday, January 30, 2011
Cenozoic Era, Quaternary Period (1.8 MYA-now)
The Pleistocene epoch is all but the last 10,000 years of the Quaternary.Several Pleistocene ice ages had huge effects. Up to 30% of the earth’s surface got covered and uncovered several times.Many familiar organisms had evolved, but there were also many that went extinct, e.g. mammoths, mastodons, and saber-toothed cats.Homo sapiens first appeared 200,000 years ago in Africa, and had spread across much of the world by around 10,000 years ago.
5Sunday, January 30, 2011
The Paleos and UCMP Websites do a great job of describing the Cenozoic
http://www.palaeos.com/Cenozoic/Cenozoic.htm and http://www.ucmp.berkeley.edu/cenozoic/cenozoic.html.
6Sunday, January 30, 2011
Human evolution . . .Humans are Primates – we all share many physical characteristics and lots of DNA.Primates include tarsiers, lorises, bush-babies, lemurs, monkeys, apes, and humans (also an ape).All primates have:
Grasping hands, most with opposable thumbs;Eyes in front of the skull, which provide an overlapping field of sight with excellent depth perception (binocular vision);A large brain size compared to body size;Flat nails instead of claws; and an . . .Unusually versatile (generalist) anatomy.
7Sunday, January 30, 2011
The complete primate lineage contains . . .
Prosimians - Lorises, tarsiers, bush-babies, lemurs, and aye-ayes (actually a type of lemur);Simians - Old and New World monkeys;Hominoids - All apes (and humans);Lesser apes – gibbons;Great apes – orangutans, gorillas, chimps, and humans;Hominines – only gorillas, chimps, and humans.
9Sunday, January 30, 2011
One more time . . .
10
And there’s actually two chimp species — the Bonobo, sometimes called the pygmy chimp, and the ‘common’ chimpanzee.
Sunday, January 30, 2011
Here’s how we’re all related:
Major anatomical shifts highlight transitions.11
Sunday, January 30, 2011
Fossils have filled in much of the detail.From left to right the
primate species depicted on the tree
are: a lemur(Lemur catta), an
adapid (Hoanghonius stehlini), a tarsier
(Tarsius bancanus), an omomyid (Shoshonius
cooperi), a proto-monkey (Eosimias
centennicus), a South American monkey
(Saimiri sciureus), an Old World
monkey (Mandrillus sphinx), a great ape
(Gorilla gorilla), and a human
(Homo sapiens).12
Sunday, January 30, 2011
Hominoid locomotionBrachiation – swinging from one arm to the other while the body dangles below.
Gibbons and Orang’s do it this way.Knuckle-walking – chimps and gorillas run rapidly on all fours with weight resting on knuckles.Bipedalism – distinguishes humans.
Adaptations include shorter arms, longer legs, supportive foot bones, fixed big toe, bowl-shaped pelvis, robust lumbar vertebrae, and foramen magnum beneath skull. 13
Sunday, January 30, 2011
Similarities and differencesMany
changes relate to locomotion.
(Chimp on left, human on
right)
14Sunday, January 30, 2011
Dietary adaptations
Size and shape of teeth, generalist versus vegetarian versus carnivore;Big sagittal crest size for strong jaw muscles, especially in vegetarians;Size of jaw bone, again biggest in the vegetarians;Prominence of bony ridge over eyes, jaw protrusion, curve of tooth row.
15Sunday, January 30, 2011
Molecular evidence concurs.Genes (coding regions) of humans and chimps are 99% identical.The two complete genomes are 96% identical with differences concentrated in noncoding regions.The only characteristic uniquely Homo is bipedal locomotion.Humans are not descended from other groups of modern apes — rather we’re all descended from a common ancestor around 4.5 MYA!Gibbons, orangutans, gorillas, and chimps are not less evolved than humans — that whole ‘primitive’ versus ‘advanced’ concept that I’ve been discussing.
16Sunday, January 30, 2011
Even our chromosomes are nearly the same
Human chromosomes are on the left, chimp on the right.18
Sunday, January 30, 2011
After the chimp genome was complete in 2005, the news hit the
stands fast and hard.For instance see: http://news.nationalgeographic.com/news/2005/08/0831_050831_chimp_genes.html and . . .http://www.genome.gov/15515096.And a nice video: http://www.cs.ucr.edu/~eamonn/DNA/dnaQT.mov helps with the visualization.
19Sunday, January 30, 2011
And just focusing on the Hominoids . . .
We are the chimps most closely related relative. As Desmond Morris would say the “Naked Ape” or as Jared Diamond puts it “The Third Chimpanzee.”
21Sunday, January 30, 2011
Hominine evolutionMolecular techniques can’t be used with most fossils — the DNA is almost always totally gone. Therefore, we . . .Must study the physical characteristics of the fossils that we can find. These include . . .Australopithecines – 4 or 5 species, bipedal. These include A. afarensis and africanus from 4-2.5 MYA. Paranthropus – had extremely large teeth, protruding jaws, big sagittal crest, 3-1.5 MYA, was an evolutionary dead end (or was it – Sasquatch?)Homo – beginning 2.5 MYA, tools, larger bodies and brains, all members are considered humans, evidence of culture, the only living species is Homo sapiens.
22Sunday, January 30, 2011
Here’s the relationships.
Interestingly, we see an adaptive radiation
followed by a dramatic fall off in
the number of hominine species at several points; e.g. 1.8 MYA up to five species coexisted in Africa, and 200,000
years ago three species coexisted in
Europe.23
Sunday, January 30, 2011
Australopithecus left more than
just bones.The “Laetoli”
footprints date from 3.7 MYA in Tanzania. They leave evidence of Australopiths’
bipedal locomotory mode.
24Sunday, January 30, 2011
The Becoming Human Website does a great job!
http://www.becominghuman.org/Their interactive video is spectacular.
25Sunday, January 30, 2011
And the PBS Evolution series is great as well.
http://www.pbs.org/wgbh/evolution/library/07/index.html and http://www.pbs.org/wgbh/evolution/humans/index.html.Be sure to check out their videos and external links.
26Sunday, January 30, 2011
The path to us . . .Charles Darwin was one of first to speculate that humans originated in Africa. And now we know this happened at least twice — the original hominines that led to all Homo, and the eventual Homo’s that migrated out of Africa to populate all the rest of the world.
27Sunday, January 30, 2011
Why did we evolve? Some say . . .Climatic shifts 12 MYA had enormous ecological consequences:
Hominids moved out of the trees and onto new savannas (but check out ‘Ardi’);This prompted selection for bipedalism;Tool use and language may have spurred evolution of a larger brain;The large brain led to culture — knowledge, beliefs, and behaviors transmitted from generation to generation;Farmers began to replace hunter-gatherers.
28Sunday, January 30, 2011
And now in the remaining time today, I want to show you part of a
great video on one the earliest known Hominin human ancestors . . .
Even earlier than Australopithecus. It was nicknamed “Ardi” for Ardipethicus, and existed around 4.6 to 3.8 MYA! The really cool thing
about Ardi is it displays an amazing combination of both modern Homo and non-
human Ape characteristics — bipedalism and a grasping big toe, as well as reduced canines!
29Sunday, January 30, 2011