4
$\begingroup$

Marsupials in the majority of the world are overshadowed by their placental cousins, with the notable exception being Australia. There they have convergently evolved many similarities to their placental counterparts, such as the thylacine which resembles the wolf, or the marsupial lion, which resembles the lion.

I am wondering: could marsupials, kangaroos or even the common spotted cuscus, for example, convergently evolve sapience?

If so, what evolutionary pressures would lead to them doing so, and what would they look like?

$\endgroup$
4
$\begingroup$

It's hard to see why they couldn't.

While it's important to remember that we don't actually know much about how intelligence evolves (we only have one instance to extrapolate from!), we think we have some pretty good guesses which seem consistant with the rest of evolutionary biology.

It seems likely that intelligence evolves most readily in social creatures where reproduction is most successful if you can dominate a social structure without injuring yourself. So brains (and, later, a golden tongue) are adaptive. This creates a more complex society, driving further development of brains and language. (Twitter, of course, reverses this process.) One biologist commented that language evolved so we could lie to each other better. Smart is successful, and successful is sexy.

I can see no reason this couldn't happen in marsupials just as well as it has in mammals. The key step would be the development of a species with primate-like social groups.

(Obviously there's more to the development of intelligence than that, since primate-like social groups probably are not unique to primates, but no one knows the details, though there are lots of theories and lots of popular books talking about it. (One common idea is that intelligence requires having hands and being capable of fine manipulation.) Still, nothing that would make it less likely in marsupials.)

As to the specific question of kangaroos, probably not. Kangaroos are grazing animals who live in herds and while there have been and are lots of species like that, none of them are ranked high in intelligence. But it appears to be possible for kangaroos to evolve into a more social species which then evolves intelligence.

As to what they would look like, that depends a lot on how quickly intelligence evolved. The physical shape is overwhelmingly determined by a species' lifestyle. A grazing animal today quickly evolving intelligence would probably still be a grazing animal and continue to be adapted to grazing, etc. There's very little reason to think that intelligence goes along with only one or a small set of body plans. (Larger heads, certainly; Manipulators of some sort (like hands) probable. Not much else.)

$\endgroup$
  • $\begingroup$ keep in mind marsupials are lacking a very important parts of the brain, the corpus callosum, so it is going to take a very long time because they have to evolve something similar. $\endgroup$ – John Mar 19 at 1:54
  • 2
    $\begingroup$ @John It will take a very long time indeed for marsupials to evolve into human beings with a corpus callosum, but the question is about the evolution of intelligence, and intelligent marsupials are likely to be different in many ways than human beings. Evolution is ingenious, and if intelligence is a survival characteristic for a long-enough time, it will find a way to evolve it another way. $\endgroup$ – Mark Olson Mar 19 at 12:22
2
$\begingroup$

Just give to this guy similar conditions to those which made Homo Sapiens evolve

$\endgroup$
1
$\begingroup$

Highly unlikely.

It takes about 7 months from a bare functional nervous system to a functional brain, in the "accelerated growth" vat that is the womb - the flow of nutrients is immense and the human fetus has only one mission: to build itself. By contrast, all the baby kangaroo has are some teats and its body will need to put extra effort in digesting the milk.

Baby's brain roughly triples in weight during the last 13 weeks of gestation, growing from about 3.5 ounces at the end the second trimester to almost 10.6 ounces at term.

...

At the same time, the cerebellum (motor control) is developing fast — faster now than any other area of the fetal brain (its surface area increases 30-fold in the last 16 weeks of pregnancy!).

I'm highly skeptical these developments can proceed outside of the protective space of the womb with the same efficiency in terms of the functional potential vs development time (this letting aside the decade long childhood in which the same brain still adjusts its fine structure).

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.