Helpless Babies

[Dean Anderson]

My daughter is now four months old (and soooo... cute! but anyway, i digress...)

After four months of life, she is still pretty much helpless. She can't yet roll over or sit up. She needs to be actively carried around constantly - she can't just 'cling on' to one of her parents. If there is something bothering her, she can't do anything about it except cry and hope that one of her parents will guess what is wrong and do something about it.

In other words she is a typical baby (except for her supernatural cuteness).

Why on earth did evolution give us such helpless babies? Being helpless for such an extended period must vastly increase the mortality rates for infants. Surely this must also be a recent development - most other primates have babies that develop much quicker than human ones and aren't helpless for nearly as long.

My guess would be that human babies have arrested development which keeps their brains in a more 'pliable' state for longer - and gives them an evolutionary advantage because they can learn more (and learn more quickly) - and that the extended period of helplessness is a negative consequence of this that's disadvantage is outweighed by the advantages the extra learning brings.

What's the current evolutionary thinking on this?

And is there any evidence of when our development shifted in this way (if it did)? I've never heard of fossilised babies - most of the fossils that get talked about are those of adults.

[Oolon Colluphid]

In a nutshell, human babies are drastically premature. And this is substantially due to the need to get an increasingly big-brained baby out through a pelvis that also has to cope with all the locomotion duties. Bipedal walking means the pelvis can't be as wide as it would 'like' to be; the answer is to squeeze the sprog out as late as possible and then look after it.

Couple of other points to bear in mind. Firstly, development is an ongoing process from fertilisation to at least post-puberty. There is no magical difference between what goes on in the womb and out of it; it's just that the individual gets its nutrition, oxygen etc from different sources after birth. The individual is still developing... and the timing of various stages can be tinkered with by evolution: earlier or later birth, infantile morphology carried over into adulthood (neoteny / paedomorphosis), and so on.

And secondly, following on: having a 'premature' baby was made possible by a suite of other evolutionary factors during the same time period and all feeding into each other: social groups, longer learning period needed, etc.

(Sorry, bit pushed for time atm, hope that helps!)

Oolon

[pz]

What? You never heard of Dart's Taung Baby (http://www.cartage.org.lb/en/themes/Sciences/LifeScience/PhysicalAnthropology/PrehistoricMan/HominidSpecies/TaungBaby/TaungBaby.htm)?

Human babies are helpless because evolution works by compromise. We got these big brains by a change in the timing of the developmental process, which had the unfortunate side-effect that we're born as useless little slugs. We don't have to be perfect to succeed, just good enough, with the advantages outweighing the disadvantages.

My first kid got all colicky 'round about 4 months, I should warn you. It was an indicator of the imperfection of evolution, and had me thinking natural selection was a darn good thing.

[the_quark]

I'd like to point out right at the front that I have absolutely no evidence for this theory, but I've always wondered if there isn't also some element in our shift away from behavioral pre-programming (relatively) towards self-training general intelligence.

In other words, I suspect that part of the reason babies are so physically incapable compared to other animals is that there is a basic conundrum to their existance: In order to buid their intelligence, they must experience the world, but experiencing the world without intelligence isn't a very good idea. By being immoble and stupid (instead of just stupid) babies force you to hang around and keep them out of trouble. In fact, a real problem with kids is when they hit that stage where their bodies outpace their brains; my 18-month-old son has figured out how to climb up into the kitchen chairs, but not down, and no amount of verbal discouragement seems to keep him from getting stuck up there many times a day. Absent adult supervision, he'd no doubt fall out trying to get down.

While on the topic of human baby evolution, as a dad I am a big, big, big fan of baby slings (http://www.parentsafely.com/over-the-shoulder-baby-holder). You put a kid in one of these in an upright position, and he's a lot more at eye level. Leaves your hands free to do things, and he can interact with you, the world, and other adults a lot more fully. Put a kid in one in a reclined position, walk around, and he goes immediately to sleep. Baby slings are actually a very ancient invention, and I've wondered if there hasn't been enough time for babies to evolve to slings - they may be the first technology humans have evolved to.

Finally, as for colic, 60% of babies are over it after 3 mos; 90% after 4 (http://www.babycenter.com/refcap/baby/babyills/77.html). Statistically, if you've made it this far, you're probably past the worst of it. My first son had one single night we couldn't get him to stop crying; the second cried every night from 2-3 months. The sling helped, though.

TQ

[doghouse]

At least in non-human animals, several other factors may be involved, in particular food supply and predatory pressure. Among mammals, many carnivores (e.g. dogs, cats) are born blind, deaf, non-ambulatory and unable urinate, defecate or maintain body temperature without the mother’s assistance– even more helpless than human infants. Their brains are relatively under-developed at birth but subsequently grow a lot.

On the other hand, many herbivores (deer, horses for example) are born with well-developed brains and are able to run within several hours of birth. In these cases, whether or not you are subject to being somebody’s lunch may have something to do with how precocious you are at birth.

Birds are also interesting. Some species are hatched with their eyes open, covered with down and able to leave the nest within several days. This is called precocial. Precocial females must be able to obtain adequate food during egg development because the egg must contain sufficient nutrients to support extensive in-egg development. But once the babies hatch they can fend for themselves relatively soon.

Others bird species are hatched with eyes closed, little or no down, and are fed by the mother (or father) for a relatively long period of time before they are able to leave the nest. This is called altricial. Altricial adults must be able to find enough food AFTER hatching to feed their rapidly developing fledglings. Also, they must protect the nest from predators while the babies develop or risk losing the entire brood.

Regarding brain size, precocial species have relatively large brains at hatching, since they must fend for themselves. Altricial birds have smaller brains at hatching, but with feeding and care by the parent(s), they ultimately develop larger brains. So it’s kind of a trade off: big brain at birth but you’re on your own and won’t develop much further. Or, small brain at birth but further development is much greater.

Parrots adopt a compromise. They are altricial but develop in energy-rich eggs like precocial species. They are born with relatively large brains that continue to develop extensively after hatching. This is similar to humans. And maybe it's no coincidence that parrots are by far the most intelligent of birds.

[Zygote]

Walking upright all the time also presents the problem of how to keep all the guts inside the abdomen. If there were a large enough opening in the pelvic bones for a mature head to fit through, there wouldn't be much to keep your intestines from hanging around your knees. Immature offsrping was the price we paid for keeping our insides inside.

Herbivores hold their unborn offspring in a nice abdominal hammock. But the pelvic opeing is so big that they occasionally get a prolapsed uterus. With predators on the prowl, though, having offspring who can follow them shortly after birth is worth the price, overall.

[Adora]

What they said. The female body might be the greatest creation on the planet ( :D ), but it's not *that* advanced to continue to carry the child further into it's gestation and growth.

That, and the supernatural-baby-cuteness I think that exists at this "premature" stage bonds you closer to your child than if it was born older and less "supernaturally cute".

[Dean Anderson]

Originally posted by Adora
That, and the supernatural-baby-cuteness I think that exists at this "premature" stage bonds you closer to your child than if it was born older and less "supernaturally cute".

Yeah - even though when I try to be objective I can see that she looks just like every other baby, millions of years worth of evolution have conspired to make be believe she is the cutest baby in the world (and therefore not defenestrate her when she won't stop crying and I am seriously sleep-deprived...)

So - purely in the interests of testing this evolutionary theory (and not at all because I am a proud father), here is the evidence for you to review for yourself...

[Oolon Colluphid]

Originally posted by Pervy Hobbit Fancier
So - purely in the interests of testing this evolutionary theory (and not at all because I am a proud father), here is the evidence for you to review for yourself...
My God, she's... hideous!

Nah, pretty cute. Not as cute as my own one was at that age, of course... ;)

Oolon

[Adora]

I have to admit, I am not a baby person, and I have seen some damn ugly babies in my time (and I mean FUGLY babies... poor things) but your baby is uber-cute.