Everything in our bodies is made of cells - bones, muscles, brain, blood. How do cells know how to build a body? Granted, each cell has a blueprint of the whole body in its nuleus, the genome. Does that help the cell know where it is in the grand scheme of things and how it should behave (divide?) for the end result to look like a human body?

If someone told ten million people to form the word "Help!" that's 100 miles wide and each person got the exact blueprint of what the end result should look like, I don't think the aliens would see a convincing message in a few months or maybe even years.

If those people are to finish their task in any forseeable future, they need some kind of a feedback loop. For instance, they could build an app that showed everyone's position on the map, so they could say "Hey, that blob looks like they're trying to be the dot in the exclamation mark. I need to move 400 meters to the south-west if I want to join them."

Do cells have similar feedback loops? Or am I too naive to think that individual cells have any say in how our bodies are built? If it's not the cells, then what is it that controls the growth of our bodies making sure we don't grow a second head and everything works in perfect harmony? Obviously, this doesn't work 100% of the time - that's when we get cancer or Siamese twins. But it works most of the time.

How does the body do it? What and where is the conductor of this billion-cell orchestra?

I am not a biologist, so please be condescending. After all, the question What controls the size of breasts? got a decent answer. I don't see why mine shouldn't.

  • $\begingroup$ Welcome to Biology.SE. Unfortunately this is not a good question for this site because it is too big. From the help center: Your questions should be reasonably scoped. If you can imagine an entire book (or this case an entire library) that answers your question, you’re asking too much. To get some idea of the size this field of research you can search on this site for the tag 'development', which is relevant to your question (currently >200 questions). IMO, if you have a strong interest in this subject you should start with the basics and work up to this very big question. ... $\endgroup$
    – tyersome
    Commented Jul 9, 2021 at 17:15
  • $\begingroup$ ... I have found Khan Academy to be a good way of getting a quick introduction to an unfamiliar (or mostly forgotten) subject area (I used them to relearn the basics of calculus). There are also many free textbooks available at the NCBI Bookshelf. Other reading you might find interesting includes this — try searching for "developmental-biology for computer-scientists" to find similar material. Hope that helps. $\endgroup$
    – tyersome
    Commented Jul 9, 2021 at 17:23
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    $\begingroup$ so basically you want us to sum up all of embryology for you? note the question about breasts is about a specific tissue. your question is far too general there is no conductor other than your DNA each tissue is controlled in a different way by different gradients and feedback loops. try starting here en.wikipedia.org/wiki/Embryology $\endgroup$
    – John
    Commented Jul 10, 2021 at 13:49

1 Answer 1


The answer to your question is huge and still evolving, involving whole fields of scientific research.

The general process of how cells develop macro-structure forms is known as morphogenesis. Within that realm of study, the science of "evo-devo" (evolutionary and developmental biology) is closely tied to the question that you've asked, as it turns out that the molecular basis of body-plans and how evolution works are closely tied together.

I would recommend that a good place to start is the popular-science book "Endless Forms Most Beautiful", by Sean Carroll, which provides a nice introduction, overview, and good intuitions for the non-biologist to start to understand what is known about this topic.

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    $\begingroup$ acapellascience's youtube channel has a song called evo-devo that nicely summarizes Carroll's book. $\endgroup$
    – Roni Saiba
    Commented Jul 9, 2021 at 3:02

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