As humans, we are not attracted to other species, such as chimpanzee's or the like; sure, we think they are cute, but not “mate” material. But for the females of the different species of ape, some have a choice with whom to mate with. For most of them there is a polygynous system, in which there is one male mating with several females. In a previous blog (http://anthropologicalconcepts.weebly.com/blog/sexual-dimorphism), I discussed sexual
dimorphism; in those in which there was a great deal of sexual dimorphism, there is a competition. It is usually the one with the most evident sexual dimorphism that is able to mate. Although, in those who do not have great sexual dimorphism, they usually live in pairs while the child is being weened. Some of those are monogamous, some also mate with other females, but for those they will stay with the female they impregnated. “Primates are amoung the most K-selected of mammal species.” K-selected means that they produce a low number of offspring so as to invest more time with the one child (the opposite is r-selected in which a large number of offspring are produced). With female primates, they spend most of their adult life “being pregnant, lactating, and/or caring for offspring.” For Old World apes their genitals swell and change colour, so in some they do no have a choice.
In some males, since they do not have invest in rearing the offspring, the want to produce as many offspring as they can; which is sometimes dangerous...to the offspring. What I mean by this is if another male becomes the leader of the pack, they will commit infanticide with the offspring that is not theirs. Even though this is highly counter-productive for the species, the males “need” to do this. Reason being is while the mother is lactating and caring for her offspring, she does not come into estrus (heat), and therefore is not sexually available. So the new male in charge kills the offspring, so that he only has to wait two to three months, and not two to three years to mate with the females. In chacma baboons, for example, they “deliberately single out females with young infants and hunt them down (image below).” All that said, it does not prove the male's reproductive fitness. What primatologists look for are two crucial facts:
- Infanticidal males don't kill their own offspring,
- Once a male has killed an infant, he subsequently father another infant with the victim's mother.
This interaction with not only their mothers, but with their “aunts” is very important for not only the infant but those females who have yet to give birth. Being with those infants is a way for them to learn what to do. But, in the case of infants who have undergone social isolation, it is obvious they need it. They have been recorded displaying self-direct behaviour, such as hugging themselves or rocking back and forth. For the social group in these primates it is suggested that the mother-offspring core gives it stability.
Please feel free to comment on what you thought of the blog, or other physical anthropological subjects you would like me to cover.
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