The curse of Lucy

Continuing the Captain Caveman series…

3.7 million years ago, two Australopithecines walked across the mud at Laetoli in Tanzania leaving their footprints behind. These hominids were clearly bipedal.

The most famous of this type of hominid is “Lucy,” whose remains were found in Ethiopia and are 3.18 million years old. Lucy was 3 and a half feet tall and could both walk and climb. She is famously held to be the “missing link” between apes and humans, a “bipedal ape,” although as with all such things, there is plenty of disagreement.

Why did apes decide to come out of the trees and walk? It may be that an Ice Age in northern latitudes caused cooling and drying in Africa, with vast swathes of jungle turning into savanna. Exposed on the open plain, hominids found that walking made them better able to see and combat danger. Enlarging brains allowed them to devise survival strategies in this harsh environment; free hands allowed them to fling objects. Natural selection meant that the smarter hominids with better bipedalism survived. Mix all of this in a million year pot and you eventually have homo.

Bipedalism led to the “curse of Lucy.” The bipedal hominid’s pelvis had to bear a stronger load, which led to a narrowing of the birth canal. This meant that birthing became more painful and much riskier. Also, to fit through the birth canal, the baby’s head (brain) had to be small, which is why human babies are such mewling, puking incompetents. Protection of mother and baby in this environment necessitated male-female bonding. And here we are.

Comments

  1. So funny to hear evolutionary teleology said out loud some times. I know it’s insipdly post-modern, but as convinced as I am that the Bible is not a scientific text, when I hear the connections made for large-scale evolutionary change, always with a modified and hence difficult to confront invocation of natural selection, this complex skeptic has to pause for a moment in his size 10.5 footsteps (not yet in the fossil record, but I keep looking for just the right mud puddle) and consider. Love and family from a compact pelvis? I should have mine squeezed.

  2. I’m afraid you’re wrong here, Sam, but I understand the romantic urge you are trying not to suppress…

  3. I read that other primates’ babies are the equivalent of 2 year old toddler humans the day they’re born.

    Human neoteny is another trait that defines us. We’re children always. =) How does that fit into this picture?

  4. Given that bipedalism > small birth canal > small-brained offspring (a logic I find hard to dispute), then the next step seems obvious: someone has to look after this useless baby, and someone has to protect that someone. Whether there’s a direct link between this fact and St. Valentine’s Day is another question.

    Tatiana,
    Tell us more about neoteny!

  5. Antonio Parr says:

    I kept waiting for the punch line for this one:

    3.7 million years ago, two Australopithecines walk into a bar . . .

    “We don’t get too many Australopithecines in this bar”, says the bartender . . .

  6. Ah, millions of years of pre-history distilled down to a paragraph, then “and here we are”! My anthropology professor would blow a gasket!

  7. Antonio,
    Admit it. You had to cut and paste Austropowepfkwefj didn’t you?

    Tracy,
    Gasket blowing is my specialty.

  8. Ronan, you’re just not skeptical enough. why wouldn’t you evolve to have babies at an earlier stage in gestation? Why not lift the birth canal forward more? What about the well known accommodations already present in the birth canal as pregnancy nears its end, what about the poor logic inherent in the teleological view that as a trait, bipedalism existed before smaller birth canals but small birth canals had to exist before bipedalism could prosper? For that matter what are the head size differentials for other simians of the period? what about head size proportionality? I’d need more convincing before I could embrace the squeezed pelvis. (that was for you, R.)

    If grand scale evolution will ever hope to actually explain human society (again, I don’t doubt evolution at all as a biological fact, but the apologia for it in the grand scale still strikes me as hopelessly simple-minded), I think it will have to do so using complex systems theory, not any silly syllogism that generates parental affection from a squeezed pelvis. No offense, Ronan, but that’s just bad science.

  9. Mark IV says:

    Ronan, now I’m confused. I’ve heard natural selection invoked to explain why men tend to be attracted to women with wide hips. You can do some anthropoligical fieldwork and verify this on Saturday nights in country music bars where a very popular song is “Honkytonk Badonkadonk”. It contains lines like “Lawd have mercy, how’d she even git them britches on?” and “I hate to see her go, but I love to watch her leave.”

    Does this mean that habitues of country music bars are not only pre-Neanderthalis but also pre-Australopithecines?

  10. “3.7 million years ago, two Australopithecines walk into a bar . . . ”

    2.5 million years ago, they learned to duck.

  11. 9. “Does this mean that habitues of country music bars are not only pre-Neanderthalis but also pre-Australopithecines?”

    My prominant brow and I resent this remark.

  12. Ronan: Ah, yes…is there Direction in Selection? The Jury is still out. There is a lot of Louis Leakey in your writing. British Stuff. Louis was not a Social Scientist. His wife Mary was.

  13. Bipedalism makes us pretty good long distance runners, which this article suggests may explain why we evolved physically the way we did. The first author is a guy from the University of Utah and I saw him speak about this paper shortly after it came out. He tells a pretty convincing story.

    Being caring parents probably isn’t directly related to our upright posture. I read The Mating Mind, by Geoffry Miller, a while ago and thought it presented an interesting hypothesis for how intelligence and human nature evolved that basically boils down to sexual selection. (The link is to a summary of the book, chapter by chapter)

    The basic idea is every individual wants to mate with the most genetically fit individual available to them in order to pass on the best genes to their offspring. In order to select the best mate possible, we choose mates based on fitness indicators. The best fitness indicators are those that incur some cost to the individual–colorful plumage; a loud, ornate song; a large territory; or a big, interesting brain. Miller’s argument is, I think, most convincing regarding human intelligence, creativity, and language skills. Fidelity has the substantial side benefits of increasing offspring survivorship, which one might argue is semi-independent of the sexually selected brain.

    Another cool topic, Ronan. Thanks.

  14. What a peculiar and irrational blend of rhetoric.

    I wonder just how does evolutionary science come to categorize any particular inherited trait as a “curse”?

    Considering the “bipedal ape” gave me equal pause. Why should any otherwise rational being so presume to denigrate real apes?

  15. I have long entertained a private suspicion, with regard to this question. Truly “smarter hominids” would long ago have asserted control over their own reproductive mechanisms, to evolve something more convenient than the current arrangement for delivering fully gestated progeny.

    Something involving velcro fasteners, or zippers, perhaps.

  16. Ah..Read Darwin’s second book on Man. The ‘strongest’ males often died defending the Group. Selection yes. The Best lived to on reproduced: Maybe.

  17. Oh, neoteny is a large part of the story of why humans are so different from chimpanzees, despite the fact that we have 90% of our genome in common. A number of the differences are in the homeobox genes and genes that regulate rates of development. Humans have many features which are present in young apes, and retain them far longer, for instance a relatively flat face, a large rate of brain growth, relative hairlessness, delayed puberty, and so on. Also, almost all mammals from mice to elephants breathe about the same number of breaths in their natural lifespans, and have around the same number of heartbeats. Humans are a huge exception, in that we live vastly longer than the typical mammalian number of breaths and heartbeats. We continue to learn at a rapid rate throughout a much extended childhood compared to apes. I just wondered, when you were telling this story of the transition to humanity, how human neoteny fit into that picture.

  18. Thomas Parkin says:

    #8

    Yes. Especially in psychology, evolution – natural selection – is easily made to explain everything and its opposite. A mother protects her young, a story is written how that trait was beneficial to the species; a mother eats her young, a story is told how that is beneficial to the species. It has become what Nietzsche said about God, ‘an obtuse answer.’ Why this: evolution willed it. What that: same. It is bordering on tautology all the time.

    Does anything happen that is not God’s will? No. Am I the king? Yes. It’s God’s will. Is everything at a point on, and a product of, an evolutionary process? Yes. Am I walking upright? Yes. Do I love my wife? yes. Do I experience God? Yes. etc. etc. You can sense it running like an acid river under everything. (Which is why, I’m quite convinced, most of the people I’ve known who really take to it, at least at the pop science level where it is encountered, are pretty miserable, often rather nihilistic little creatures.)

    What gets my goat is that I don’t think it really tells us anything useful about life. If you want to know why a man is violent you don’t need to go back to the Ice Age – you generally only have to observe the man’s father. Can evolutionary psychology really describe to us the ‘thoughts and intents of our hearts’ better than Freudian psycholgy, or Romantic poetry, or the Bible, or a simple man thinking about himself for a couple hours?

    ~

  19. Thomas et. al.

    I am truly at a loss to understand why the obvious reality of small-brained human babies requiring male-female bonding to ensure their survival is the crazy idea you are suggesting it to be.

  20. Most of the people I’ve known who really take to it, at least at the pop science level where it is encountered, are pretty miserable, often rather nihilistic little creatures.

    I’ll take that as a compliment.

  21. Thomas Parkin says:

    Ronan,

    It isn’t crazy – it’s irrelvent. *wink*

    Anyway – I can’t beleive I’m up at 5:30 am posting on BCC. I’ve got a bad history with online discussion – I’ve just been reading some of that history. Wish I’d known about x-no-archive. I get really vicious,- but I haven’t been that person in a long while, and I didn’t mean to start now.

    ~

  22. #19, Ronan, it’s because it sounds like a Kipling Just-So story dressed up with a wee dollup of probability theory (conveniently flooded into irrelevance by several 10^6’s) and physical determinism. It sounds like a fun story to attempt to describe something we understand very little, and it serves as an indicator of devotion to a view of human experience that lacks drama, power, or spirit (this is the human side speaking). It’s like something out of Crick’s great paradox book, which was unreadable.

    So the answer is that it’s just not rigorous enough, and it thus remains mythic, so if that’s the case, you’re allowed to ask what the myth attempts to establish, and that is that a core aspect of being human derives solely from the biomechanics of bones.

  23. I forgot, Sam, that you don’t like funerals-as-political statement. Romantic!

  24. Interesting post, thanks Ronan.

  25. #19 It’s like trying to leap a canyon in two leaps.

  26. #13 “sexual selection” in higher animals? Sorry, mostly rape by the strong. In Primitive Man with Culture, mostly Group Sex, not “mating”. Dads did not bond with kids or females. Mother’s Brother the more likely Male figure.

  27. Okay, weird that this has devolved into that sort of discussion. I want to take it back to the science, if I may. There’s a really interesting realization about sexual selection that I’ve never read of naturalists making, though it’s completely obvious once you think of it. Sexual selection is always described as female choice drives male traits which are counter-survival and yet they are pro-reproduction because females like them. If you look at the situation logically, that’s putting the cart before the horse.

    Female preferences are themselves traits that are selected for. That’s the horse that comes before the cart. If the females of the species decide they like male traits that are unfit, then those females will have fewer or less-successful offspring and the traits (male unfit trait plus female preference trait) will not tend to propogate. So how do we solve the conundrum of the peacock tail, huge antler racks, stotting, etc.? How can we explain the fact that some male sexual traits exist which LESSEN the chance of the male’s surviving? Isn’t it true that a large and ungainly tail makes a peacock easier for predators to spot, and makes it harder for the peacock to get away, and yet it’s still attractive to females? Such traits aren’t advertising the possibility of fit offspring overall. After all, the male offspring will share their father’s handicap. What such traits advertise is the possibility of fit DAUGHTERS. Because this male is so strong, healthy, and fit that he can survive even with this metabolically expensive and ungainly tail, it means his daughters are going to be extremely fit, for they will inherit his overall strength, endurance, and health without the handicap.

    What this has to mean is that fit daughters are more important to gene propagation in the long run than fit sons. Otherwise, the female preference for mates with large beautiful tails would die out.

    Nobody but I that I’ve ever read seems to understand this fact. If you think about it logically, though, it’s completely obvious. Female preference doesn’t just arise from nowhere. It’s a heritable trait the same as any other, and so natural selection of course must work upon it.

    The only reason I can see that other naturalists miss this concept is they are mostly male? Does that make any sense? It doesn’t seem to. But otherwise I can’t explain it.

  28. “The only reason I can see that other naturalists miss this concept is they are mostly male?” Well…add me to your list. “If you think about it logically, though, it’s completely obvious”. Take it Ronan, you started it. Good Night.

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