Aquatic Ape Human Ancestor Theory

Aquatic Ape Theory - What is it?

A Brief Summary of AAT - key arguments

A Brief History and Key Proponents of AAT

Current Aquatic Evolution Theories

Timeline

Alternative theories of human evolution

Wikipedia and the scientific community

. Anatomical Evidence
... Bipedalism
... Birth and babies
... Brain
... Breath control
... Fat
... Fingers, toes and feet
... Furlessness
... Hair and baldness
... Kidneys
... Menopause
... Nose
... Olfactory sense
... Pachyostosis
... Paranasal Sinuses
... Platycephaly
... Sexual features
... Surfer's ear
... Sweating
... Tears
... Underwater vision

. Diet
. Language & Song
. Sleep (USWS)
. Waterside environments
. Sea Gypsies

. Homo erectus - shallow diver

. Fossil evidence
. Paleoecological evidence

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Menopause

Female killer whales, like female humans, experience menopauseAnimals almost always continue to reproduce until they die. There are just three exceptions that we know of: humans, short-finned pilot whales, and killer whales. In all three species, females lose the ability to have children at an average middle-age, but continue living for decades after. Human females go through menopause when they are around 45-50. Female killer whales go through menopause their 30s or 40s but can live for up to a century. But what sense does it make in nature for a species to live maybe half their lives without being able to pass on their genes?

One theory about why killer whales experience menopause [1] is that it provides the older generation of matriarchs a better chance to look after their existing children and grandchildren. Orcas, like humans, invest a lot of time and energy into rearing single offspring that take many years to fully mature. In the sea, it is dangerous to leave a young whale unattended while the parents hunt, so the larger the family group or pod, and the more elder females who aren't breeding there are in that pod, the better the likelihood of the young whales surviving to maturity.

"One of the most popular explanations, first proposed in 1966, involves helpful grandmothers. Even if older women are infertile, they can still ensure that their genes cascade through future generations by caring for their children, and helping to raise their grandchildren.* There’s evidence to support this “grandmother hypothesis” in humans: It seems that mothers can indeed boost their number of grandchildren by stepping out of the reproductive rat-race as soon as their daughters join it, becoming helpers rather than competitors." [2]

But what about humans? There is no scientific concensus about why we alone of all the primates should go through menopause, although it is argued that it is difficult to observe if and when menopause may occur in wild animals.

"Economic subsidies that older women are observed to supply to their daughters and grandchildren point to the distinctive selection pressures likely to have favored post-menopausal survival in ancestral populations." [3]

So, it's clear that menopause helps the young survive, especially in humans when one pair of hands is needed per child. All the other primates seem to manage foraging and finding food quite well with their infant on their back and their toddler close by.

But they are on land. In the water, even babies that float and toddlers that can swim need an adult keeping a close eye on them. An early human ancestor who spent most of her day in the water, foraging beneath the surface for shellfish, would not be able to do this. This is when a non-breeding grandmother comes in very useful! [4]


 
Website: F. Mansfield, 2015

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