November 2: Mammalian Heritage Day

Finally a fake holiday I can get behind. We humans in our evolution find ourselves benefitting fully from our mammalian heritage. Mammals appeared on the scene around 500 million years ago and have diversified into many different forms since. Consider their (our) primary characteristics. Being warm blooded confers a crucial independence from ambient conditions, an independence humans have taken to an ultimate degree. It is not just that mammals have adapted to many different environments around Gaia, including returning to the ocean, but we have further enhanced our independence by controlling and changing these ambient conditions, perhaps to own detriment but then no species continues forever.

Consider another characteristic: live births. This is especially important for three reasons. First, infants born viably but immaturely permit an incredible amount of post-partum growth. The benefits of this are astounding: increased brain growth and size and critical periods of maturation where experience affects brain development in deep ways. Second, parenting becomes a lot more than regurgitating food into infant mouths and then kicking them out of the nest. Oxytocin, a most important hormone for parenting energy and prosocial behaviors, has been around, according to some estimates, for over 530 million years. Over the course of evolution mammalian brains developed the capacity to respond more powerfully to this hormone—parenting and family life became more prominent in any adaptive success, and that leads us to the third reason: If you want to raise more intelligent children and pass on to them the benefits of prior generations’ experience, birth them live and immature, maintain a nurturing family structure, and extend their juvenile period so that they do not begin to reproduce until they are a decade or so old. The discovery of controlling fire was not really that big of a deal; the passing on of this technique, however, was; just ask Prometheus.

Our immediate (relatively speaking) ancestors who showed the culmination of these characteristics are the primates who appeared around 53 million years ago. That means mammals evolved for 450 million years before our large brained, visually oriented, socially engaged, and quick intelligence kinfolk appeared and then simians appeared a few million years after that. Our line split off from the great apes around 8 million years ago and our partners, the dogs, appeared around 3 million years ago. Fire was important because it furthered this trend. Cooking food releases more calories, making digestion more efficient, and more energy from food powers increased brain capacity. Fire warms us and draws the family group to the hearth. Civilization began at the hearth (and it looks like it will die in committee).

So this November 2 take a moment to reflect on our genetic heritage and thank a mammal, any mammal, all mammals for continuing this genetic stream and tend to your hearth.

bonobo1

We sing a song of mammals today . . .

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