It’s hard to believe that newborn kittens grow up to be predators. Cuteness is only part of it. These blind and deaf little furballs have a good sense of smell but little strength or coordination. They can’t even control their body temperature at first!
In contrast, a caribou calf can travel cross-country within a few hours of birth. Its lifestyle demands this.
People are somewhere in the middle. Unlike kittens, babies are born with eyes and ears open, yet it still takes us a while to develop the ability to sit up, let alone walk.
The technical name for animals that bear helpless young is “altricial.” It’s related to the word “altruism,” and the parents certainly do have to make sacrifices for their young.
Since there are obvious advantages to having youngsters that require less care after birth, like the caribou, why are some placental mammals altricial?
The short answer is brain size; also, the need to find a balance between feeding your young and protecting them from predators.
Here is more information.
How kittens develop
Adult cat brains are proportionately bigger than a caribou’s. But at birth the brain of a kitten weighs less than a quarter of its full-grown weight.
This probably comes as no surprise to anyone who has ever seen a kitten.
What’s inside those little heads will grow along with the rest of the body, and in the process, somehow acquire and store all the information they need to become apex predators (domestic cats are usually the dominant small predator in a human-dominated environment).
During the first month of life, a kitten learns about the world through smell and touch, developing attachment to the mother cat and interacting with litter mates.
By month two, the world is one big playhouse. The Internet community is not unaware of this life stage:
It’s adorable, but these kittens are instinctively learning and practicing survival skills–skills that the adult cats will never need if they stay close to loving and responsible human friends.
The outside world is harsher. Playtime lasts until about age six months for feral kittens–then Mom drives the males away from the den. If they can survive on their own, the young toms will eventually establish a territory somewhere else.
This seems horribly cruel, but such dispersal is common in mammals. It’s probably also a major reason why cougars have such a wide range today – from the tip of South America up into the Canadian Yukon!
Young domestic she-cats set up their territory closer to home, when they reach adulthood, and may become part of a feral cat colony.
Luckier kittens–those born indoors or found by someone–usually settle into their forever home around eight weeks, right after weaning.
However, cat breeders and savvy owners know that the kittens will be more comfortable around people later on if they are handled a little bit every day from around the ages of two to seven weeks.
No one knows why. But cats that don’t get that human contact at just the right time in early life tend to be a lot more anxious and wary; they even may have behavior problems.
Young cats don’t keep journals, so we have no idea what’s going on in their heads. But it’s obvious that the slower development of altricial animals, with its mysterious timing and unknown processes, has important long-term effects.
A cognitive buffer?
When feral kittens are about three months old, Mom starts bringing them live prey for hunting practice. It’s probably not a coincidence that this is also the age when a kitten’s brain reaches its adult size.
But even as the kittens stumble along, learning the age-old techniques of predation, they already see a slightly different world than their mother does.
Over the last three impressionable months, they have absorbed details of things as they are now, not as they were when Mom was born. Since the natural world is very complex and interconnected, these altricial youngsters have probably picked up on subtle changes and/or interconnections that not even their mother is aware of.
Some experts call this the cognitive buffer effect. It may or may not make a big difference later on in life, but it does raise a question.
Domestic cats always live near people, and we do make sudden, sometimes drastic changes in the environment. Could this built-in adaptability between generations be a reason why cats have kept up with us down through the years?
That’s an open-ended question. The benefits of having a relatively large brain aren’t obvious. It might also be connected to how animals forage for food (such an association has been found in bats) or even have something to do with social development.
But there must be benefits; otherwise, cats and other altricial animals would have gone extinct long ago–it’s very “expensive” in biological terms to develop so slowly after birth.
Too expensive, apparently, for precocial animals–those like caribou whose newborns (or newly hatched young’uns) are rarin’ to go.
Nourishing and protecting the young
Altricial and precocial animals are two extremes of a whole spectrum of developmental styles that researchers are trying hard to understand today.
And as mentioned above, people are roughly in the middle. So are parrots, oddly enough. Long ago in this dangerous and unpredictable world, our ancestors (and Polly’s) worked out a balance between feeding newborns and protecting them.
Finding food without becoming food yourself is quite a challenge for any living being in the wild. And on top of that, in order to avoid extinction, you must bring new life into the world and make sure that it survives long enough to reproduce.
Animals have solved this problem in different ways. Precocial caribou, for example, keep their young inside until they have developed enough to stand and walk. This is a very good solution to the predator problem, but it is physically very demanding on the mother. Too, it limits brain size.
As we’ve seen, altricial cats take months to develop after birth, ending up with comparatively big brains. But again, this is rough on the mother cat. She must hunt enough on her own to bring the kittens to term and then to produce milk for them. After that, she has to bring food back to the den as well as catch something for herself.
Including some rays now and then:
Life will always find some way to survive and reproduce, even if humans don’t fully understand it. Caribou continue to have calves because it works for them. Cats have kittens, and that works out, too.
People are in the middle of the spectrum, but unlike all other living beings, we just can’t resist wondering what it’s all about.
Featured image: Christian Holmér, CC BY 2.0.
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