How to Grow a Human - Philip Ball

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is not accounted for very clearly in the single-minded dissection to the molecular level. Even as the tide of information surges relentlessly beyond anyone’s comprehension, the organism as a whole has been shattered into bits and bytes. Between the thriving catalog of molecules and genes, and the growing cells under my microscope, there yawns a gulf that will not be automatically bridged when the missing facts have all been supplied. No, whole-genome sequencing won’t do it, for the living cells quite fail to declare themselves from those genomes that are already in our databases … The time has come to put the cell together again, form and function and history and all.

      It is precisely the multivalent, multiscale implication of the word “life”, too, that creates the tensions, ambiguities and ambivalences about what it means to “grow a human”. We are thereby “making a life”, but not “making life”. That same truth is spoken in jest in a cartoon by Gary Markstein in which two white-coated scientists contemplate IVF embryos. “Life begins at the Petri dish!” exclaims one embryo; “Cloning for research!” demands another. “Even the human embryos are divided”, sighs a scientist.

      This is the struggle we face in reconciling our notion of life as human experience with the concept of life as a property of our material substance. We are alive, and so is our flesh. While those two visions of life were synonymous, we could ignore the problem. Having a mini-brain grown in a dish from a piece of one’s arm tends to make that evasion no longer tenable.

      It’s no wonder that different cultures at different times have had such diverse attitudes to the connection between the human body in utero, forming in hidden and mysterious fashion from something not remotely human-like, and the human body in the world. The insistence by some people and in some belief systems that “life begins at conception” is a modern utterance, often claiming firm support from the very science that in fact shows how ill-defined the idea is.

      But the tension is an old one, as demonstrated by preformation theories of the human fetus. This was an anthropomorphization of the cell as explicit as that in cartoons that attribute voices and opinions to human embryos in petri dishes. Intuition compels us to look for the self in the cell. An insistence on locating it instead in our genes – as cell biologist Scott Gilbert puts it, to see “DNA as our soul” – comes from the same impulse. Perhaps we must be gentle in dispensing with these superstitions. Aren’t old habits always hard to shake off?

       CHAPTER 2

       BODY BUILDING

       GROWING HUMANS THE OLD-FASHIONED WAY

      So far, nothing beats sex. Biologically, I mean. If you want to grow a human, you need a sperm and an egg cell – the two cell types called gametes. And you need to get them together. That’s an objective towards which an immense amount of our culture is geared.

      In describing the process in which a fertilized egg develops into a person, I hope in this chapter to give back some of the strangeness, the proper unfamiliarity, to embryology: to show how removed our individual origins are from the comforting intimacy of the gracefully curled fetus that is generally our first ultrasonic glimpse of a new human person.

      We are folded and fashioned from flesh in its most basic form, according to a set of instructions that is far removed from a kind of genetic step-by-step. We are shaped from living clay according to rules imperfectly known and often imperfectly executed, and which orchestrate a dance between the cell and its environment.

      But there are many things you can potentially fashion from clay, if you know how to work the wheel. As we come to understand more about the emergence of the human ex ovo, we perceive new possibilities, new beginnings and routes and directions. And we change from watchers to makers.

      * * *

      There is no new narrative of human-growing that does not need to reckon with the preconceptions (so to speak) created by sex. Mary Shelley could not, in her day, make that context explicit – but Victor Frankenstein’s terror of his wedding night tells us all about the psychosexual undercurrents in his onanistic act of creation. I won’t therefore attempt the same evasion as the school biology lesson by beginning the embryo’s tale with sperm meeting egg; by that stage sex has, as we’ll see, already imposed itself on the story.

      We should in any case be continually amazed, surprised and possibly even a little proud at how imaginatively we have elaborated, ritualized and celebrated the urge to procreate. This shouldn’t be seen so much as proof that evolutionary psychology can “explain” culture – the banal observation that because of our instinct for sexual reproduction we write stories like Romeo and Juliet and create entertainments like Love Island – but rather the opposite. Evolutionary psychology by itself offers a rather threadbare and reductionist narrative for understanding the rich tapestry of culture. Sure, we can attribute to the sexual drive everything from a worship of lingams in Indian tradition to the Tudor enthusiasm for prominent red codpieces,1 the hegemony and variety of internet porn and the exquisite faux-pheromone concoctions of perfumeries. But then we will have not really said much that illuminates the particulars of any of those diverting cultural phenomena, will we?

      It’s tempting to suppose that the bare biology of reproduction is quite distinct from the human mechanics and its attendant rituals, its messiness and epiphanies and calamities. But we rarely make any statement about biology, and least of all about the biology of making humans, that is devoid of a culturally shaped narrative. If we imagine we can start talking about new ways to grow humans (and parts of humans) that do not inherit some aspects of the stories we tell about how we do it already, we are fooling ourselves.

      The old ideas of generative male seed quickening the passive female “soil” are evidently invested with patriarchal stereotypes. Within Christian tradition, conception long struggled to find accommodation with religious thought, being simultaneously a miraculous gift of God (and thus a moral obligation) and the fruit of sin. Within this view, the only “pure” conception in the history of humankind was one that took place two thousand years ago without intercourse and without seed, to dwell on the gestation of which was to risk heresy. And medieval theology willingly lent authority to the idea that to expel male seed not directed towards procreative possibility was even worse than to couple in lust, for it was liable to be taken up by demonic succubi and bred into monsters.

      These were tales not just about the social side of sex but about its biological and medical aspects too. Until the nineteenth century, the health hazards of masturbation were considered a plain medical fact, as was the idea that a fetus in the uterus could be damaged by a mother’s bad thoughts. Probably every age has imagined itself mature beyond this mixing of science with folk belief and sociopolitical ideology, but let’s not make the same mistake.

      So how does the sperm fertilize the egg? Why, the plucky little fellow has to race along the vaginal passage,2 out-swimming its (his, surely!) peers in a Darwinian competition for survival. There sits the egg, plump and alluring – and in he dives, kicking off the process of becoming one of us. As Life’s science editor Albert Rosenfeld wrote in 1969, people are made from “the sperm fresh-sprung from the father’s loins, the egg snug in its warm, secret place; the propelling force being conjugal love.” (I think you’ll find it is actually hydrogen ions crossing cell membranes.)

      We see this story not just in children’s books about how babies are made, but (less obviously) in some biology textbooks too, where the active role of the sperm and the passivity of the egg cell is typically stressed. It’s wrong. There is now good reason to think, for example, that the sperm’s entry into the egg is actively mediated by the egg (although even this description still somewhat anthropomorphizes the participants, imputing aims and roles). The fastest sperm are not necessarily the victors, because sperm needs conditioning by the female reproductive tract to make it competent to fertilize an egg. There is increasing evidence that in many species the female can

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