Human Evolution

Before We Begin…There are two major schools of beliefs when concerning the

history of our planet and the origin of man, one being Darwinism (The Big Bang and Evolution, etc.) and the other being Creationism (God did it).

Each belief has the right to be expressed in the U.S. and the study of human evolution is required by the MS Biology I State Curriculum, although MS is considered to be part of the “Bible belt”.

But ponder this…could it be both? Could a higher being start the cogs that would turn to shape our world (initiating the Big Bang)? How long is a day to the heroes of the Old Testament? If God worked for six days, but Earth is 4.6 billion years old, could a day to God be a couple million years to us? So, could God have created organisms and set them off to evolve and multiply according to His plan?

No one will ever know the true answer while on this plane of existence. Just remember that your opinion is just that…your opinion. It is all protected by the constitution as long as you remain within reason of the law.

The Evolution of PrimatesPrimate Ancestors Evolved During the

Age of Dinosaurs• Fossil evidence indicates that a small insect-eating

mammal with big eyes and tiny, sharp teeth, resembling a shrew lived about 80 million years ago, during the age of the dinosaurs. These ancient mammals were the ancestors of the first primates, the mammalian group that includes prosimians, monkeys, apes, and humans.

• The first primates had:– Grasping hands and feet – enable them to cling to their

mothers, grip limbs/hang from trees, and seize food.– Forward placement of the eyes – produces and

overlapping binocular vision that enables the primate brain to judge distance more precisely (depth perception) that comes in handy for leaping from branch to branch.

First Were Prosimians• Prosimian – member of a group of

mostly night-active primates that live in trees. Modern prosimians include lorises, lemurs and tarsiers.

Primates Evolved Specialized Traits• Many Primate species became diurnal (active

during the day).• With being active in the day, the rise of

specialized cone cells in the eyes led to color vision which gave rise to the development of a larger, more complex brain. These are monkeys. Monkeys, together with apes and humans are called anthropoids.

Monkeys• Monkeys were among the first primates to have

opposable thumbs (digit that stands out at an angle from the other fingers and can be bent inward to hold objects).

Emergence of the Apes• Fossil evidence indicates that humans evolved

from the same evolutionary group that gave rise to the apes. Apes have larger brains than monkeys and no tails.

Early HominidsPrimates Evolve Upright Walking

• Early primates walked on four limbs, but hominids are primates that can walk upright on two legs.

Australopithecines• Australopithecines – earliest know direct

ancestors that were fully bipedal (walk upright on two legs). Also showed a large brain, which had a greater volume relative to body weight than an ape.

The Oldest Hominid• In 1992, another nearly complete (before that

was the specimen “Lucy”) fossil skeleton was found in Ethiopia by the American anthropologist Tim White. This fossil is still being reconstructed but has been estimated to be 4.4 million years old!

The Genus HomoThe First Hominids that Left Africa

• Our genus, Homo is composed of at least 3 species. We are the only surviving species. Homo evolved from australopithecines more than 2 million yrs ago.

• Homo habilis is considered the oldest, but Homo erectus or Java man was found to have left Africa (found in S.East Asia)

Homo sapiens Arose Recently• Latin homo, meaning “man” and sapien meaning “wise”

(early H. sapiens were the Neanderthals, called so bc the first H. sapien fossil was found in Neander valley in Germany)

• Two hypotheses based on fossil evidence:– Either Homo erectus groups living in Africa, Europe and Asia

interbred and H. sapiens arose all over the world simultaneoulsy or

– H. sapiens appeared in Africa, then migrated to Europe and Asia, replacing H. erectus as they migrated.

• Either way, our ability to make and use tools effectively has been important to our success in the animal kingdom. Through culture, we have learned to change our environment to suit our needs rather than changing ourselves in response to our environment.