Humans are always concerned about shape and size. Shape, because we always wish to look better than what we looked yesterday; and size, because, well… Size matters…
My context here is regarding the brain size. Does brain size matter? Also, what is the ideal brain size, or rather, is there an ideal brain size at all?
We all know from our day to day interaction that some people take long time to understand things while others are able to understand the exact same concept in a slightly better and shorter duration of time. Individuals differ in their ability to understand new ideas, to adapt in new environment, to learn from experiences, to plan and to act accordingly. When it comes to brain size, humans or biologically speaking homo sapiens are always considered advanced than any other living organism. Homo sapiens generally get most of the credit when it comes to intelligence and brain size. But this article is about an animal which has been very pacific in discrediting humans of this unsaid superiority.
Yes, you heard it right its an animal, a marine mammal to be specific. One of the cutest looking seals in Antarctica, which lives in this snowy and icy continent, named Weddell seal. Weddell seal pups likely possess the most adult-like brain of any mammal at birth. Pups of the weddell seal have the largest brain on this planet. By the time they are born their brain had already reached more than half of the adult brain size. “Why is it so necessary for such new born pups to carry such large brain?”
Life under water is less fascinating and more challenging. For outliers like us it is simple and beautiful but marine mammals need extra processing capacity to orient themselves in a 3-D underwater environment, and tend to have larger brains than comparable terrestrial species.
Ice-diving, that too under a closed ice is extremely dangerous for mammals, as they risk drowning if they cannot locate exit on time. Many adult mammals also never try this icy dive but exceptionally 3 species do this- The Baikal seal, The ringed seal, and The Weddell seal.
Still the question has not been answered, as to –
Why do baby weddell seals try such icy swims at the age when they should be lingering around their mother?
The most likely answer to this question is- It appears they have no choice!! Weddell seal mothers attend their pups for only 40-50 days. After that the pups are on their own. With such a small window of time, pups are under a lot of pressure to master the under-ice navigation skills which they would need for rest of their life. This is the reason nature has gifted them with potential large brains to face the dark, freezing, lethal water which for rest others is the source of life.
But, everything that we achieve from nature has its own cost. For pups, the larger brain size comes with an unwanted cost of higher metabolic rate thus asking for higher calorie demand which is required for the maintenance of their brain. For eg: a pup weighing about 30 kg requires approximately 30-50 gm of glucose per day in order to survive. Fortunately, like every other mother, the baby pups guardian is sufficiently able to fulfil this need. Nature has so evolved that the mothers milk is almost exactly matched to the babies’ caloric needs. Weddell seal milk supplies about 39 gm of sugar per day. Although, this feeding pattern leads to significant weight loss in the mother putting her survival at risk.
Evidently, the babies’ brain and its better survival thrives at the cost of her mother’s life.