Monday, 10 October 2011

Sea monkeys - the first freedivers

Aquatic Ape Theory
The theory, put forward in 1960, suggests that humans spent a good deal of their evolutionary history living a semi-aquatic life. This is notion that has intrigued me for a long time, especially as the theory, in my experience at least as a graduate of Zoology, does not form part of the modern teaching. Instead we are taught that the evolution of humans took place primarily on the savannah.

The theory is based on the idea that a branch of primates began to exploit the sea shore environment after probably being forced from the forest and savannah as a result of competition. Firstly paddling in the shallow water searching for fish and sea urchins for food, we moved into deeper water to search further, using the water itself to support our not yet fully upright bodies. This is thought to explain how we became bipedal, which is easy to imagine, given the need to keep one’s head clear of the water to breathe.

An interesting study found that in order for a brain to grow and develop fully it requires a supply of Omega 3 (found in fish oil) and Iodine. These nutrient can only be found in the marine food chain. The theory suggested that nutrient from the marine environment were essential for brain growth.

Breath control
Very few land mammals, including other primates, have the capability to hold their breath. Humans breathe involuntarily most of the time, as you probably are now, unconsciously. We breathe voluntarily when our own thoughts take over and breathing becomes a conscious activity.
We are part of a small group of mammals which can both consciously and unconsciously breathe. We share this talent with otters, for example and seals and sea lions. These are what are termed as amphibious or aquatic mammals whose ability to breath hold developed in order to be able to hunt underwater and exploit niches that very few other mammals could. Other mammals, such as brown bears (a seals closest land based relative), are able to hold their breath for short periods while scavenging for fish, and a species of macaque can dive for food.

Being born
The human diving reflex is strongest in new born babies. When water comes into contact with sensory receptors around the cheeks and nose, the throat closes off allowing no water to enter the lungs and heart rate slows down after a time, conserving oxygen.

What next?
The theory of the Aquatic Ape is still to be proven beyond doubt. There exists compelling evidence for the theory, both behavioural and physical and the above is only a snapshot of the basis for the argument. It’s something that will remain of great interest to me while exploring my body’s own ability to adapt further, in the short-term at least, to the aquatic environment.

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