BIOL359 Lecture Notes - Lecture 27: Homo Sapiens, Lumpers And Splitters, Euarchontoglires
5 May 2018
School
Department
Course
Professor
Human Evolution
➢ Summary of scientific explanation
• Dawn of humans down from the trees bigger brain tools
➢ Origin of species (24 November 1859) origin of species debate concept that we have evolved,
descendants from apes
➢ Darwin as a caricature
• Darwin had completed a draft of the origin of species by 1844.
• He did not publish it until 15 years later because he knew it would result in personal
attacks. He worried about how others would think about it
➢ Racial caricatures
• Social Darwinism: has been used repeatedly to justify one ethnic group’s abuse or domination
over another.
• Such attitudes involve incorrect assumptions about human evolution
➢ Huxley vs. Wilberforce
• As the 1860 British association meeting, Huxley debated the origin of species with bishop
Wilberforce, mouthpiece of anti-evolutionist Owen.
• Question was asked: Did you descend from apes on you grandmothers or grandfathers side?
➢ Human Evolution is about mechanism, means of inheritance (genetics)
• What will be discussed: where do humans fall in general classification?
• When did the human/homid/hominin lineage diverge from other great apes?
• How diverse is the human lineage throughout time?
• When and where did homo sapiens first appear?
How many races of homo sapiens have evolved
➢ Phylogeny of Mammals
• Mammary glands females produce milk to nourish developing young, hair
• Monotremes egg laying
• Marsupials pouch maturation
• Placental Mammals specialized, embryonic organ, attached to the wall of the uterus
➢ Phylogeny of Eutheria
•
Afrotheria, Xenarthra
developed in Africa,
•
Euarchoniglires, Laurasiatheria
evolved in western and eastern portions of the northern
hemisphere supercontinent Laurasia
• Primates are one of the many groups belonging to
Euarchontoglires
primates have and
thumbs that oppose, stereoscopic vision (good at judging distance – eyes at the front of
head)
• Great apes (defined as having no tail) appear in the fossil record about 20 mil years ago
• Hominids appear between 5-8 million years ago
• The genus Homo is about 2.8 mil years old
• Modern humans appear in the fossil record is about 300, 000 years old (Morocco) … very
recent evolution
➢ Lumpers vs. splitters (types of Taxonomists)
• Lumpers like fewer, bigger categories and fewer species
• Splitters like smaller units and more species
• Taxonomists fall somewhere on the continuum from extreme lumpers to extreme splitters
find more resources at oneclass.com
find more resources at oneclass.com
• This means that there are different opinions on how many species, genera and families of
great apes should be recognized
• If the splitters are right then the post
H. ergaster
history is complex with at least six
descendant species: 4 in Africa, Europe and western Asia
• Lumpers recognize two species
H. erectus and H. sapiens.
Older forms are archaic
Homo
sapiens
• There is no correct solution to the nomenclature problem at this point in time
➢ Changes in the number of Taxa
• There were fewer fossils known but many of them were placed into different species in
different genera, splitters were active
• Then lumpers sorted through much of what was known, and the phylogeny became rather
simple
➢ The first great apes: “
Dryopithecines
”
• Lasted from 20-10 mybp
• Gave rise to two branches: one in Africa (gorilla, chimps, hominins) and one in Asia
(orangutan)
• The oldest to appear in the fossil record about 20 my bp
• They were small arboreal primates about the size of a big cat or dog, fossils found in
Africa and Asia
➢
Ramapithiceus
: thought to be in direct lineage to us
➢ We are in line with Pongidae
➢ Blue: problem: this GAP is being filled in with very recent finds of early Hominid fossils. Before the
gap, only
Dryopithecines
and
Pongidae
were known
• Pre-1900 we knew about Neanderthals and homo erectus
• 1924
Australopithecus Africanus
,
• our life span
Sahelanthropus tchadensis
,
• 1944/2017 oldest hominids have been found most recently
•
➢ Hominid Phylogeny
• Bipedal Locomotion an important part of human origins was the evolution of bipedal
locomotion.
• Gorilla knuckle walk. Chimps can stand walk on two legs but are not really evolved to do
so efficiently.
• All hominids stand and walk on two legs, although with varying degrees of efficiency
bipedal locomotion is not as efficient or as fast as quadrupedal locomotion… so why did it
evolve?
Rift Valley Splitting of Lineages
➢ All early hominid fossils come from the Rift Valley of east Africa. Gorillas and chimps come from
central Africa and western forests.
➢ When did the African
Dryopithecine
line split?
• Chimps and gorilla stayed in trees. East Africa dried out and the forest got broken up into
small patches and turned into savannahs and grasslands
• As it dries out, there is open space between the trees, so the great ape has to get down
from the tree to move to another tree. Pattern continues, and it continues to get drier and
more open. By the end of this period, the genus homo begins to appear.
➢ Changing Selection pressure in the rift valley
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Summary of scientific explanation: dawn of humans down from the trees bigger brain tools. Origin of species (24 november 1859) origin of species debate concept that we have evolved, descendants from apes. Darwin as a caricature : darwin had completed a draft of the origin of species by 1844, he did not publish it until 15 years later because he knew it would result in personal attacks. He worried about how others would think about it. Racial caricatures: social darwinism: has been used repeatedly to justify one ethnic group"s abuse or domination over another, such attitudes involve incorrect assumptions about human evolution. Huxley vs. wilberforce: as the 1860 british association meeting, huxley debated the origin of species with bishop. How many races of homo sapiens have evolved. Phylogeny of mammals: mammary glands females produce milk to nourish developing young, hair, monotremes egg laying, marsupials pouch maturation, placental mammals specialized, embryonic organ, attached to the wall of the uterus.
