Pazzi Hard!!

my lecturers have been very clear and very insistent that bipedalism evolved first and then allowed tool use, tool use did not spur a transition to bipedalism, the fossil record is Clear On This Point

and what I do not understand is: if bipedalism is so completely wonderfully energy-efficient and optimal, why are there so few bipedal things? How come lions and gazelles and giraffes and buffalo aren’t bipedal? Why aren’t other savannah species selected for energy-efficient locomotion too?

You know when creationists talk about how an eye couldn’t possibly evolve gradually, because half an eye is useless and a waste of resources and worse than no eye at all?

They’re wrong about eyes; a single photoreceptor cell (usually just an evolutionary ‘tweak’ away from a regular epidermal cell with biochemistry that happened to be photosensitive) is actually useful and great, and more is better. If you imagine breaking a modern wing in half and attaching it to a bird, “half a wing is useless” sounds true, but it stops sounding true when you realise that halfway to a wing doesn’t look like a modern bird wing but broken in half, it looks like a slightly enlarged membrane between a limb and your body that gives you just an extra half second of glide time when you jump.

But there *are* adaptations in this class of things, where it’s great if you have full-blown X but shitty to have half-baked X. As you might imagine, they are quite rare, because as the creationists correctly observe, if half-X is maladaptive there is no path to arrive at X through gradual adaptation to an environment. And yet bipedalism is of this class. How?

Well, you wanna know what it looks like to have enough bipedal foot structure that you decide to go adventuring around in the savannah on two feet, but you haven’t got the pelvic structure to make it efficient yet? YOU CAN’T RUN. You are literally incapable of moving faster than a kind of slow awkward lope. Your back kills all the time because your bones are all pointed the wrong way and your back muscles are trying to keep you upright. Your ankle and leg bones take far more pounding than they were ever optimised before and occasionally shatter. You’re unbalanced and ungainly and frankly sort of pathetic, and at very high risk from predators (to repeat: RUN AWAY IS NOT AN AVAILABLE STRATEGY).

Why would anything go through a long gradual process of getting much shittier and then eventually getting better, since evolution can’t plan or foresee? WRONG QUESTION. Whoever told you evolution was a slow gradual constant drift was a dirty rotten liar, just like all your other teachers from when you were twelve. More commonly, evolution involves long periods of relative stability where the organism is pretty much as adapted to its niche as it’s going to get, and then something changes and there’s a very rapid response. Or it involves successful populations dispersing widely over a landscape, then becoming distinct reproducing populations which lost genetic contact with each other and diverging, and then there’s an environmental change and they reconnect and sometimes they happily interbreed and sometimes one of the divergent branches drives the others extinct and disperses itself widely and rinse and repeat.

What happened was, basically:

Hi we’re early hominins and we just love hanging around in trees and we’re proud to say we’ve been hanging around in trees now for a couple million years and we haven’t changed a bit, slightly bigger skulls aside, we’re basically just per- what the fuck? WHAT THE FUCK? WHERE DID THE TREES GO?? WHY IS IT SUDDENLY SO DRY???? oh my God I can see nothing but grass and I am having to walk around on my hind legs all the FUCKING time and FUCK FUCK FUCK THAT’S A LION FUCK PANIC RED ALERT oh okay we’re bipedal now I guess, that was quick, oh well, all fine, carry on

Somehow we survived when a change in environment pushed us into a new ecological niche. The selection pressure was strong enough to make us acquire a really quite extensive range of mods to make bipedalism work, but not strong enough to make us dead.

Of course, “strong pressure to adapt somehow” doesn’t necessarily mean “strong pressure to adapt in this specific way we know is really good”. Early hominins who lived before the forest shrinkage have been shown to have a few bipedal adaptations. We weren’t sure what the hell they were doing with them, so we looked at chimps. Turns out chimps display short-distance carrying behavior - as in, picking up an object and carrying it. They don’t carry tools and can’t move far bipedally, but what they do do is pick up a valuable resource like a choice bit of prey and haul it off with them, away from the group of moneys fighting over the rest of the prey. So before the forests collapsed, there was a mild selection pressure to be able to use only your hind legs for a short stretch so that you could carry something in your arms, and when they collapsed, individuals good at that behavior were better at surviving the savannah and evolution just slammed its foot on the gas pedal until you get obligate bipeds.

So, a species that wasn’t forced into a rapid niche change like that, wouldn’t evolve an initially-painful thing like bipedalism. What about all the other species that made the same change as the same time as us? Eh, many went extinct, that happens a lot with ecological change, but the ones who survived didn’t do bipedalism.

Points to those who said it was about evolution having different starting points to build on, y'all were correct. No matter how awesome and efficient and optimal bipedalism is, evolution only cares about whether the next tiny step in some random direction increases or decreases how many offspring are produced. Evolution “looks” for the NEAREST solution that counts as a solution, not the best solution.

For a species of monkeys that were forced to spend less time in the forest and range wider and already had some variable locomotion abilities, evolution went for bipedalism. Bipedalism may have enabled the future awesomeness of humans with its efficiency and head stability and what have you, but evolution made it happen just because it was the local maxima - its awesomeness is a lucky side effect.

But where monkeys used short bursts of bipedal movements to carry things, another species might use something more convenient for them - say, a lion might pick up and carry things in its mouth, and if there was a selection pressure to be better at carrying the lions might end up with bigger mouths, but “become bipedal” is very unlikely because half bipedal is worse than no bipedal at all.

Basically, monkeys had the preconditions for bipedalism, nothing else did. (Note that this does not make monkeys special - the ancestor of any species with an unusual adaptation, from giraffes’ long necks to penguins’ Arctic-water-proofing feathers, was a thing that had the preconditions for that adaptation when nothing else did.)

Bipedalism didn’t happen because it was awesome, it became awesome because the range of adaptations it supports turned out to be a package that turned into, well, us.

…Notice that we are not actually the only bipedal species. Notice what they mean when they say things like, “Bipedalism leads to the ability to carry things leads to tool use leads to bigger brains”. On a naive reading, it means “bipedalism is a part of the tech tree and once you’ve bought it you can get hands optimised for holding tools”, and if it says this then you are right to be confused as to why perfectly good bipedal emus do not also have spears and control of fire.

When you realise that evolutionary studies is so full of ridiculously many caveats and preconditions that lecturers just omit them and assume you know they’re there, you start interpreting what they say more like, “In a species that already dabbled in just a tiny bit of bipedalism, bipedalism was the only way to go when the niche changed, it was way better for the new niche then the old way of locomotion, and given the likely presence of some proto-tool-like behaviors like throwing rocks or poking things with sticks, it created an adaptive opportunity to better fit this particular environment by improving on the tool behaviours using the new physiological advantages.”

Also god I learned a lot in that hour. Why does time spent *not* talking to biological anthropologists have to be a thing? Talking to biological anthropologists is the BEST.

Human locomotion is not particularly energy efficient! It takes us more energy to walk or run than it does for most mammalian quadrupeds, but our energy use curves look pretty different from theirs. 

If a horse goes for a trot, its trot (like all its gaits) has a U-shaped energy curve. It costs more to trot at slower speeds, goes down to a most-efficient pace, and then comes back up. At a certain point, it crosses over the energy curve for the horse’s next gait, and the horse will (left to its own devices) start to canter or gallop.

Human WALKING has a U-shaped curve like that, but human RUNNING does not, and that is damned strange for a mammal. Our friend Smil says: “the energetic cost of human running is relatively high, but humans are unique in virtually uncoupling this cost from speed”. That particular aspect of things is a direct side-effect of bipedalism: we can vary our breathing in ways that quadrupedal animals (who have supporting legs all attached to their breathing apparatus) cannot. Basically, we are the evolutionary equivalent of cartoon characters who can spin their legs really fast. So we aren’t as efficient at running as a horse who is going at its optimum pace, but we can speed up and slow down and it won’t cost us much, which is not true of the horse.

Not incidentally, this is why many humans practiced (or still practice) persistence hunting. If you are less efficient than that delicious antelope, but you can make it run at its least-efficient panic speed while you trundle along at a nice constant rate, you can exhaust it.  

The lecturers conflated tool use and tool making. Tool USE is observed throughout the animal kingdom. Tool MAKING is said to be primate-specific (we ignore corvids in this scenario.) note that this isn’t hominid-specific, though. Tool MAKING is not a function of bipedalism; it’s a function of having your hands free. These are two very different things. Now, it’s certainly true that tool MAKING - in the form of shaped bones, flints and stones - postdates bipedalism in the fossil record, but we must note

1. A shaped blade of grass or a shaped branch counts as a tool, and does not reliably fossilise; 2. Behaviour is notoriously bad at fossilising; 3. Scientists must acknowledge the biases of the fossil record in geology and paleontology, so don’t think that anthropologists are going to be allowed to get away with it.

So tool-making, like bipedalism, is something that popped up occasionally in our lineage and is still practiced by our living relatives. It became fixed in our lineage, and is distinctive to hominids, but it was not dropped on us by the Hand of God. Very very few things are.

We also note that birds are bipedal, and are something of the original biped. We are kind of hipsters in that sense. (BEHOLD! THE MAN!)

But, you see, birds generally don’t have HANDS.

carrying tools is nbd, modern chimps make and stash some wacky shit and have been known to wear a favorite termite stick behind their ear to keep it. a clever tool guy is going to find a way to do the clever tool thing no matter how comfortable it is for him to stand up.

but you combine that big brain with the slow but efficient swing gait of a walking human, and what you get is a predator who can mosey ominously after you until you just drop dead.

there is literally no animal on earth that can out-stubborn a human. and even a pretty average human with no special training can walk hours without dipping into their long-term energy reserves or experiencing significant fatigue. an experienced hunting team in peak health? they’ll go a week. nothing can survive that. hell, i recall myself as a 12-year-old kid, just some suburban rando who played a few team sports, and my dad the office worker with the weekend martial arts habit, easily separating, directing, and following a full-grown buck across maybe 20 miles of boreal forest, deliberately passing up several good opportunities for kill shots in favor of herding it closer to where we left the car. that wasn’t the heroic effort of a whole tribe, that was a fun weekend for a couple joes with one decent bow between them. for early humans, organizing a perfect hunt was no doubt as fun and interesting as sports are to us now, and more invigorating than exhausting.

a hunting wolf, on the other hand, will drop a chase after a mile or so. just. welp. nevermind.

one mile.

This occurred to me because I was thinking about how colas are advertised now versus how they were advertised in my childhood in the 80s – now there’s stuff like the emojis on Pepsi bottles and the names on Coke bottles, whereas when I was a kid the big thing was athletes and movie stars drinking cola. And they were marketed in that way in the 80s because the idea was “You could be as cool as this dude if you drank Coca Cola.” 

This marketing doesn’t work on the younger generation, because we don’t give a fuck about being as cool as That Dude. Because we were raised with this weird emphasis on self-esteem. Boomer style marketing doesn’t work on Millennials (or on a significant portion of GenX) because Millennials can’t be courted by the idea that consuming something will change their self image or their image in other peoples’ eyes. I mean yeah we’re all broke, but we understand that buying something won’t make us feel less broke. The idea of “Treat Yo Self” works because it’s based on the idea of buying something that will give you pleasure rather than status. We don’t need status. We make our own, or we find it irrelevant. Because: self-esteem. (Older generations tend to mistake this for self-absorption, because they don’t have it and thus believe it cannot be a virtue.)

BUT SAM, THEN WHY DO I HAVE SUCH ANXIETY? you ask. WHY AM I SO OBSESSED WITH MY FAILINGS?

Well, because you are conscious of them in a way that previous generations aren’t. You’re aware of your self-esteem issues because self-esteem as a concept is so familiar to you. Someone raised without that emphasis on self-esteem in schools and childhood media buys a status-maker because they’re not aware that’s what they’re doing. It’s an unconscious connection. They don’t understand why they feel inadequate, so they can only turn to the media to guide them towards a feeling of adequacy. Millennials know why they feel inadequate, and they know buying something won’t solve that. 

Buying something may bring pleasure, but we know it won’t bring a permanent solution to our feelings of inner turmoil, and so our spending habits are radically different and our interaction with advertising is conditional in a way our parents’ isn’t. We want it proven that what’s being sold to us will either solve a real problem or bring a real pleasure, and if you can’t do either of those things, go fuck yourself. Because we have self-esteem. 

Of course also we’re broke. But that didn’t stop previous generations, who just invented the credit card and kept going. 

In the movement it was then applied sloppily, without consideration, on a mass-production scale, in a one-size-doesn’t-fit-anyone mentality. Like a machine spitting out smocks that are all size 9 but made with lycra so in theory they can SORT OF stretch to actually be on any body but oh god there are like maybe 15% of humans in the middle that actually look good and are comfortable, and maybe 30% of humans around that 15% who can more or less get by and fuck everyone else. 

It was treated as “ah, praise = self-esteem = the coin I can put in the machine to get a High Achieving, Well-Balanced Child.” And everyone went YAY! and went about their business. 

And it fucked us up. Bad. 

One of the things I’m very firm on is I don’t lie. I’ve taught music, and I’ve had a bunch of other situations, and if something went wrong I’m gonna absolutely acknowledge it. I am also going to go “okay no, you’re right. That scale wasn’t as good as the scales you heard Georgina practicing while you were waiting for your lesson. Georgina is two years older than you, and started music when she was 5. This is not an appropriate benchmark to set for yourself, and also, you can BE GOOD ENOUGH without having to compete with Georgina. When I just told you ‘that was great’, I meant ‘you have improved significantly and by the measures that we talked about last class, which were evenness of rhythm and legato connection, that improvement is in fact great’.” 

I break it down to that. Which has been an important part of working through this stuff.