Primate Evolution Section 16.1 Primates

Daily Objective Understand that Primates share several behavioral and biological characteristics, which indicates that they evolved from a common ancestor.

16.1Primates Humans Apes Lemurs Monkeys

Characteristics of Primates Manual Dexterity- flexible hands and feet. The first digits on Primates hands and feet are opposable. Opposable first digit; either a toe or thumb is set apart from the other digits. Senses- Binocular vision allows for primates to have a greater field of depth perception and better judgment of relative distance and movement of an object. Most primates are diurnal; active during the day and have color vision. Primates that are nocturnal have black and white vision.

Characteristics of Primates cont.. Locomotion- Primates have flexible bodies and limbs. When on the ground all Primates but Humans walk on all four limbs. Complex brain and behaviors- Primates tend to have large brains in relation to their body size. Many primates have problem-solving abilities, and well developed social behaviors. i.e. grooming and communicating.

Characteristics of Primates cont.. Reproductive rate- Most primates have fewer offspring than other animals, and the majority of Primates have single births at one time. Compared to other mammals pregnancy is long, and infants depend on the mothers for a great amount of time.

Primate Geographic Distribution Non-human primates live in tropical regions. The loss of habitat is threatening populations in those areas.

Primate Groups Primates are a large diverse group of more than 200 living species. They are divided into two sub groups. Strepsirrhines- “the wet-nosed group” The most “basic” subgroup. Includes the Lemur. Haplorhines- “dry-nosed” Includes large-brained diurnal monkeys and hominoids (gibbons, orangutans, chimpanzees, gorillas, and humans.)

Where do Humans fit in? Humans are included in the great ape family. They are then classified in a separate subcategory of hominids called hominins. Hominins are humanlike primates that appear to be more closely related to present- day humans than they are to present-day chimpanzees and bonobos. Only one species survives today.

Primate Evolution Arboreal adaptation- many scientists speculate that primates evolved from a ground-dwelling animal. Primate ancestors- Data suggests that the first primates lived about 85mya, when dinosaurs roamed the earth (Cretaceous period) But fossils do not appear until 60 mya (Eocene epoch)

Primate Evolution cont.. Diverging primates- Sometime around 50mya the anthropoids (great apes) diverged from the tarsiers (haplorhines primates) Displacement- Many early strepsirrhines were exctinct by the end of the Eocene epoch. It is a thought that since the arthropoids were larger and had bigger brains, that they outcompeted some of the strepsirrhines species for resources.

The appearance of monkeys occurred at the end of the Eocene. Monkeys are split into two categories; Old world and New World monkeys. Scientists hypothesize that the New World Monkeys diverged from the line that gave rise to the Old World Monkeys between 35 and 25 mya. Primate Evolution cont…

Daily Objective Describe several Hominoids and Hominin features

Section 16.2 Hominoids to Hominins Describe hominoid and hominin features

Hominoid characteristics They are the largest primates. Largest brain size to body ratio. Broad pelvises Long fingers No tail Non-specialized teeth. (Their molars have distinctive pattern scientists use to distinguish hominoid fossils from other primates.)

A few facts about hominoids Include all nonmonkey anthropoids- the living and extinct gibbons orangutans, chimpanzees, gorillas, and humans. The earliest hominoid fossils appear in the fossil record only about 25 mya at the beginning of the Miocene. (middle of Cenozoic)

The fossil record for hominoids is so sparse, so scientists also examine biochemical data. They compare the DNA of living hominoid species and researchers conclude that gibbons likely diverged first from an ancestral anthropoid, followed by orangutans, gorillas, chimp, bonobos, and finally, humans.

Chimpanzees and bonobos are the closest living relatives to humans. All three share at least 96% of their DNA sequences. The human lineage and the chimp lineage diverged about 6 mya.

Hominin Characteristics Hominins have big brains with more complexity in parts of the brain where high- level thought occurs. Thinner, flatter face Smaller teeth Lengthened thumbs, flexible wrists, and manual dexterity Bipedal- they can walk upright on two legs

Hominin cont.. Homo sapiens (us) evolved around 200,000 years ago and were preceded by several other species of Hominin. A hominin is any species that is more closely related to a human than a chimpanzee. Meet Lucy!

Daily Objective Investigate the comparison between DNA of humans, chimpanzees, gorillas, and “a common ancestor”

Procedure 1) “synthesize DNA strands according to the following specifications. Each different color of paperclip represents one of the four bases of DNA. Adenine (A) = Guanine (G)= Thymine (T)=Cytosine (C)=

You are synthesizing DNA strands by connecting paper clips in the proper sequence according to specifications listed by each group member. When you have completed your synthesis attach a label to Position 1 and lay your strands on the table with Position 1 on the left.