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13.10 Evolution of Primates |
| Humans belong to the scientific order named Primates, a group of over 230 species of mammals that also includes lemurs, lorises, tarsiers, monkeys, and apes. Modern humans, early humans, and other species of primates all have many characteristic similarities as well as some important differences.
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| Many of these characteristics evolved as adaptations for life in the trees, the environment in which earlier primates evolved. These include more reliance on sight than smell; overlapping fields of vision, allowing stereoscopic sight (three-dimensional); limbs and hands adapted for clinging on, leaping from, and swinging on tree trunks and branches; the ability to grasp and manipulate small objects (using fingers with nails instead of claws); large brains in relation to body size; and complex social lives. | |
The scientific classification of primates reflects evolutionary
relationships among individual species and groups of species: 
| | The first
primates are divided into 2 evolutionairy groups based on nasal
characteristics: | | A. Strepsirhine (Greek: Turned-nosed) |  | B. Haplorhine (Greek: Simple-nosed) | - Evolved earliest and are the most
primitive forms.
- Representatives include lemurs, lorises, and other groups of species
all commonly known as prosimians.
- Their moist nose is connected to the upper lip, which is
connected to the gum, giving them a limit to the facial expressions
they can manage.
- Their brain to body ratio tends to be smaller.
- Their brain's olfactory lobes are larger, lending to the notion that they have a stronger reliance on smell.
- Their snouts are generally elongated giving them a dog-like appearance, although this is true of some monkeys too.
| - Monkeys and apes evolved the earliest from this type of which the
most primitive living representative is the tarsier (see pic.).
- Anthropoid (Greek: of human likeness) primates evolved
from these ape ancestors.
- Their upper lip is not directly connected to their nose or gum, allowing a large range of facial expressions.
- Their brain to body ratio is significantly greater.
- Their
primary sense is vision. Most species are diurnal (the exceptions being
the tarsiers and the night monkeys) and have trichromatic color vision.
- They have a reduction in the olfactory system.
- Their hands and feet are more generally adapted, with
specialization only for locomotion, such as the hooked hands common to
gibbons and orangutans, or the human bipedal feet.
| | Small binocular view | Large binocular view |  |  | | Lemurs | Tarsiers are the only living representatives of a primitive group of primates that ultimately led to monkeys, apes, and humans. |
| | | Anthropoids (Greek: of human likeness) are divided into 2 evolutionairy groups based on nasal
characteristics:
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A. New World monkeys
| | B. Old World monkeys & Apes
| Platyrrhine (Greek: flat nosed) | Catarrhine (Greek: narrow nosed)- downward pointing nostrils
| - South- and Central America, and the Caribbean Islands.
| - Africa and Asia.
- They are generally diurnal
| - Most New World monkeys are small have long tails that are often prehensile and almost all are arboreal.
| - Longer hind legs than forearms.
- Monkeys have tails but their tails are not prehensile.
- Apes don't have tails.
| | - Prominent buttock pads that they can sit on.
| - Many form monogamous pair bonds, and show substantial paternal care of young.
| - Most species show considerable sexual dimorphism and do not form a pair bond. Most, but not all, species live in social groups.
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| - Apes rely on vision rather than smell, and thus have shorter noses than some monkeys.
- They are diurnal
- Apes have a large brain to body size ratio compared with other animals.
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| - The Great Apes are able to use tools, and use language.
| - Marmosets, capuchins, and spider
monkeys.
| - Humans and Apes together make up the hominoids.
| Small nasal intersection, Side way's focused.
| Larger nasal intersection and horizontal facial masking, Frontal focused. |  |  | | Capuchin | Bonnet Macaque |
 | Hominoids are divided into 2 groups: Hylobatidae Small or so-called lesser apes of Southeast Asia, commonly known as gibbons and siamangs. | | Hominidae (hominids) Humans and Large apes: chimpanzees, gorillas, and orangutans. | - Are arboreal, and probably fastest of all primates, swing from branch to branch.
- They usually associate in family groups consisting of male, female, and
several offspring of various ages; following a strict daily routine.
Male dominance does not exist within the group.
| - Lack of a tail.
- Share more than 97% of their DNA with the modern human genome
- Exhibit a capacity for language or for simple cultures beyond the family or band.
- The theory of mind including such faculties as mental state attribution, empathy and even empathetic deception.
- All of the great apes are now known to use tools.
| | Small horizontal facial masking by fur | Large horizontal facial masking |  |  |
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| | | | Humans
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| topic is in progress |
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The
purpose of this site is to present questions and new ideas about
the above subjects.
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