Humans vs Primates
Humans vs primates (or "humans as primates") is sometimes included as a minor topic in first-level courses in biology e.g. A-Level Biology, human biology, human anatomy & physiology and related subjects that may be preliminary requirements for entry into careers in health sciences or animal welfare.
In biological terms humans are sometimes described as highly evolved primates because of the similarities in the physical and biological structures of the bodies of humans and modern primates such as monkeys, apes, orang-utans, gorillas and similar animals, in addition to humans perceived superiority over those primates.
What is a primate ?
The strict scientific definition of a primate is lengthy, complex, and in some respects still being debated. Short dictionary definitions of the word "primate" tend to avoid the scientific subtleties by answering the the question "what is a primate?" in the form of a list of examples of primates:
Short (non-scientific) definitions of a primate
- any of an order (Primates) of mammals that are characterized especially by advanced development of binocular vision, specialization of the appendages for grasping, and enlargement of the cerebral hemispheres and that include humans, apes, monkeys, and related forms (as lemurs and tarsiers)
- a member of the most developed and intelligent group of mammals, including humans, monkeys and apes.
(Cambridge Advanced Learner's Dictionary)
- a mammal of the order Primates, which includes the anthropoids and prosimians, characterized by refined development of the hands and feet, a shortened snout, and a large brain.
(American Heritage® Dictionary of the English Language, 4th Ed.)
Biology students might appreciate a stricter definition in the form of a list of characteristics of primates. See (1.), below.
To consider humans as primates it is useful to compare the similarities and differences between modern humans and apes incl.:
- Characteristics that primates typically have in common
- Human anatomy compared with ape anatomy
- Human social behaviour compared with ape social behaviour
- Respects in which humans seem to be more advanced than apes
(1.) Characteristics primates typically have in common
1. Opposable thumb
meaning that thumbs can be held in position opposite to the attached fingers.
2. Hands and feet can grasp
i.e. "prehensile" hands and feet
3. Fingernails instead of claws
as opposed to other mammals such as bears, dogs, both large and domestic cats, and many other smaller animals have sharp claws at the end of each digit whereas primates have comparatively flatter fingernails and very sensitive tactile pads on palmer surface of the digits.
4. Flattened face resulting in two eyes next to each other pointing in the same directions
as opposed to other mammals such as horses, deer, elephants, dolphins and many others whose eyes are on either side of the head/face pointed in opposite directions, i.e. one eye points to the left and the other to the right.
Eyes located side-by-side as in primates makes possible stereoscopic vision, which is important for depth perception.
5. 32 teeth in permanent heterodont dentition
"heterodont" refers to animals that have several different types of teeth, e.g. incisors, canines, premolars, and molars. This indicates feeding/hunting specialization in a species (compared with other species that are often considered more primitive e.g. certain bony fish, amphibians, and reptiles).
6. Single pair of mammary glands (breasts)
as opposed to many other animals such as e.g. cats, dogs, pigs, rabbits and squirrels whose adult females have multiple pairs of mammary glands, which is important for feeding large litters of many young.
... and other features that are not usually required knowledge for school-level biology courses. For a description of what is meant by the word "primate" in more technical scientific terms see the "definition of a primate" at: http://www.leeds.ac.uk/chb/lectures/anthl_08.html (from Leeds University, England).
(2.) Compare human anatomy with ape anatomy
- Limited proportion of skin covered in hair
e.g. top, back and sides of head, armpits & genitals (adults), sometimes chest & limbs (adult males).
- Dense hairs cover most the skin
except face, plantar surfaces of feet and palmer surfaces of hands.
- Skull supported on top of vertebral column
- Skull hangs forward from vertebral column
- Cranium larger than face
(cranial volume twice that of apes)
- Face larger than cranium
- Facial Structure:
- small eyebrow ridges
- protruding nose
- flattened jaws
- large lips (beneficial for facial expression)
- Facial Structure:
- prominent eye ridges
- flattened nose
- very large jaw (for eating)
- thin lips
- Walking upright (called "bipedal gait") enhanced by:
- legs longer than arms
- wide pelvis (relative to apes)
- ability to straighten the knee
- arched feet
- large buttocks (relative to apes)
- Shuffling on all fours ("quadrupedal gait") supported by:
- long arms (proportionately longer than in humans)
- narrow pelvis (relative to humans)
- knees bent - to greater or lesser extent
- flat, fat, feet (relative to humans)
(3.) Compare human social behaviour with ape social behaviour
Human - Social Behaviour
Ape - Social Behaviour
- Social groups not necessarily associated with survival e.g. nationality, cultural/hobby interests, social media such as Twitter, etc.
- Social groups are based on survival needs only e.g. cooperation re. finding food, care of young and defence of group
- Advanced Communication - taking various forms e.g. of sound, writing, art and use of complicated technologies.
- Communication based on a limited range of sounds and gestures
- At least some humans are highly mobile - by making use of modern transport by land, sea or air.
- Live (in the wild) within relatively small territories
- Occupy specific homes, either individually or in small (usually family) groups. Sometimes said to have "fixed" homes but some groups of humans are or have been nomadic - even in those cases they usually travel with a home/shelter or the components needed to create one e.g. tent-like constructions.
- Do not occupy specific "homes" or dwelling places
- Can make tools individually and manufacture advanced devices collectively e.g. producing component parts (possibly at different locations) assembling and testing or calibrating them, finally transporting them to even more locations for use.
- Do not make tools e.g. by changing the shape of objects in their environment for use for a specific purpose. However, may use objects as tools to perform simple tasks.
- Can control and make use of many forms of energy, e.g. fire for heating spaces and cooking food, wind for travel by sail or conversion to other types of energy, and even converting nuclear energy for use in many ways e.g. in homes and businesses.
(4.) Human advances: Respects in which humans seem to be more advanced than apes
1. Larger brain
2. Different shape of skull
Flatter face rather than face projecting forwards
It has been argued that this enables humans to display a wider range of facial expressions but (if they could communicate it to us) might apes disagree ?
Is this really an "advance" or just a "difference"?
3. Bipedal gait
Human adults walk most naturally on two legs.
In comparison some other primates can walk on two legs but most normally use all four limbs and have greater need to do so because they move vertically around trees as opposed to humans moving around predominately on the flat or vertically via lifts and stairs (designed for humans to maintain upright posture). As an example of an exception to the "rule", see the YouTube clip for an example of a gorilla that has become known for bipedal movement.
4. More advanced / nimble use of hands
Actual use varies between individuals but the ability of some humans to produce finely detailed objects by hand proves that this is at least possible for the human species to levels of skill and detail not known to have been achieved by primates such as apes.
5. More advanced forms of communication
Such as using:
- Spoken languages,
- Sign languages/gestures,
- Written communication incl. written languages as well as mathematical, chemical and other scientific notation, also
- (More recently)
Use of advanced technologies such as radio and television, telecommunication, electronic communication, radar etc.
- Some people might include psychic communication e.g. "remote viewing" while others would argue that such abilities would need to be wider-spread and better-developed to be included. More importantly for this topic, there would need to be an agreed way to test and compare the prevalence of such abilities within and possibly also between humans and various species of primates and no such criteria is widely accepted.
6. Use and production of (better) tools
i.e. better than those of primates generally
7. Human cooperation in such social aspects as ...
- Production of food,
- Care of young,
- Building structures and defence of groups against outsiders.
Controversially, while it is easy to think of examples of these and other areas of cooperation, some might argue that it would be more "advanced" and "civilized" not to need so much cooperation in all of these areas. For example, many women would prefer to be financially able to spend time looking after their own children instead of arranging for other people - sometimes several other people at different times and in different places - to do so instead