Just like the title says: Strictly from a biological perspective, what is the functional expectation of a human being.

No religious or philosophy-based answers will be accepted, we are talking biology not religion or philosophy.

Answers involving excessive psychology will be frowned upon unless found to be exceedingly insightful. (The brain is a biological entity)

If you are considering claiming this to be too broad or unanswerable consider the hypothetical question "what are the functional expectations of human feet" which can be answered fairly easily by a child with no formal training in biology. In my actual question I simply ask about the feet and the other parts attached to them.

Edit: Originally this question was titled "Strictly from a biological perspective, what is the purpose of a human existence." To clarify the question i have changed it to "Strictly from a biological perspective, what is the functional expectation of a human being."

Despite the concerns raised with the use of the word "purpose" the question was serving its purpose with the answers I am seeing. I did have some reservations about the word "purpose" as well, but I thought I would try it and see what others thought.

So if a human stomach has the overall functional expectation of mechanically and chemically breaking down and digesting food, what would be the overall functional expectation of a human as a whole? I am looking for not so much of psychologically specific functional expectations and more of physical functional expectations.

For instance a house cat's functional expectations are generally considered to be sleeping, eating, reproducing, socializing, hunting, etc.


closed as too broad by Oreotrephes, von Mises, MattDMo, Ilan, user560 Apr 19 '14 at 11:49

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • 2
    $\begingroup$ Adding the line "from a biological perspective" does not make this any less of a philosophical question. I would argue that the question "what is the purpose of feet" is also philosophical, but as shorthand most people will interpret that as 'what function(s) do feet serve the body' which is a biological question. It doesnt work for your question. What function do humans serve _____? Serve what? Serve themselves? Serve elephants? This question is too broad if biological, off topic if philosophical $\endgroup$ – von Mises Apr 18 '14 at 20:07
  • 2
    $\begingroup$ Although "What is the purpose of human feet" and "What is the purpose of human existence" have the same word pattern, they are quite distinct English sentences, even before the biology question. The first can be answered with what good feet do for people. The second asks what good people do for something (what?) I would -1 this if I had the rep on this site (I have lots on math) Looks like a troll to me. Biology and purpose rarely belong in the same sentence. $\endgroup$ – Ross Millikan Apr 19 '14 at 4:07
  • $\begingroup$ I think maybe the question is badly phrased. You may want to rephrase without using the word "purpose", which implies a rationally-planned intention before the development of the item to which purpose is ascribed. As biology does not accept that any such rational planning occurred, strictly speaking nothing can be said to have purpose in a biological context. $\endgroup$ – Jules Apr 19 '14 at 4:10
  • 1
    $\begingroup$ First you have to define "purpose"... $\endgroup$ – keshlam Apr 19 '14 at 4:23
  • $\begingroup$ Sorry guys I don't see any way of further modifying the question without changing the intent of the question. It is an important question and was answered well. Do whatever needs to be done. $\endgroup$ – Beo Apr 20 '14 at 11:22

I will start with a quote from François Jacob, a French geneticist:

The sole ambition of a bacterium is to make two bacteria.

The same reasoning can be extended to all life on Earth, including humans.

There is no purpose to human existence, in the same way that there is no purpose for life at all. Life is there because it can. It works, chemically, physically and thermodynamically, given the physical conditions present on Earth.

Biology does not give any moral reason for our existence. It only describes what is there. Using experimental techniques we can infer the purpose of the human feet. All we need to do is to remove the feet of a human subject and see what happens. The subject will be unable to walk, and therefore we will be able to infer that the feet's purpose is to enable locomotion. In biological research, we usually remove or silence genes or proteins from an organism to infer their purpose. We then observe the phenotype. Most of the time however, such an experiment does not give any information on the purpose of the gene because its function is not obvious enough to be observed.

In the same vein, one could remove humans from the Earth and see what happens. If something changes for the worse on Earth, then we would be able to infer that our purpose was to prevent such event from happening. Obviously, such an experiment is impossible to perform, therefore we will never know what is our purpose, neither will we know whether we actually have a purpose.

  • 1
    $\begingroup$ I would have given a two-word answer ("To reproduce."), but +1 for making the answer long enough to satisfy stackexchange requirements and even throwing in an apropos quote. $\endgroup$ – Carey Gregory Apr 19 '14 at 0:48

Purpose requires a sentient being to have intent. There is no biological reason to suppose there is any purposeful intent behind life.

If you hold otherwise, perhaps inquire of the fellow or lady or other you suppose is responsible.

Just because a child can give an answer to a question doesn't mean that the answer is accurate, or that the question truly is well-formed enough to answer well.

  • $\begingroup$ +1. That there is an evolutionary benefit to feet does not imply that they have a purpose, as purpose requires forethought. The same can be said of life's tendency to reproduce itself: you can argue that it is a basic characteristic of life, but that doesn't elevate it to the status of a purpose, because purpose implies design and there is no scientific basis for believing that any such design occurred. $\endgroup$ – Jules Apr 19 '14 at 4:08

In the context of evolution, the only "purpose" that a thing can serve is the role it plays in the process of reproduction, selection and mutation.

So, "what purpose do feet serve"? Naively: the formation of part of the human body as feet serves to increase the likelihood of the survival and reproduction of humans, by supporting the way we move and stand. Even more naively, the child wouldn't talk about survival and reproduction -- to a child the purpose of something is whatever benefit it is seen to cause, so the purpose of feet would be "walking".

"What purpose do humans serve"? Naively: to survive and reproduce. With more nuance, since we know about symbiotic evolution: to increase the likelihood of the survival and reproduction of various species, including but not limited to humans. For example humans have been pretty bad news for North American magafauna, but pretty good news for wheat.

On this basis of symbiosis you could reasonably conclude that the "purpose" of animals (or at any rate most bilateral animals) is to serve as a habitat and food-gathering mechanism for their gut-flora. Or that the "purpose" of most eukaryotes is to do the same for mitochondria. Or less fancifully, that the "purpose" of living organisms is to provide a stable environment for RNA and DNA to reproduce.

It's ultimately a question of perspective and as such subjective. "Purpose" really implies intent, which absent religion or philosophy is pretty hard to pin down. But when talking about feet and other biological characteristics we use "purpose" as a shorthand for "benefit which explains their being selected for".

As such, providing an environment for DNA to reproduce is right up there as a candidate for the purpose of life in general, including humans. Humans then are a variation within this general goal, that seems to be doing OK for the time being. This is more or less the theme of The Selfish Gene. You can easily question Dawkins's views on religion and philosophy, but (despite some disagreement) his ideas on genetics were pretty well received as far as they went.


That all depends on the perspective from which you view the question. For example, from the perspective of a human being the purpose of human existence may be to make more humans. From the perspective of a herd of goats the purpose for human existence is for the humans to bring food and water, care for kids, shovel out the barn, talk nicely to them, scratch them behind the horns where they can't reach, and give them something to snicker at. Cats are much the same but will sometimes allow their bellies to be scratched, don't have horns, and are to the best of my knowledge unable to snicker.

And of course all this assumes, on what only be termed hear-say evidence, that humans exist. "Ah", you say, "but I am real - I have form - I have substance - of course I, and by extension the entire human race, and in fact the entire universe, exist!". Perhaps, but then again perhaps not. What if what you perceive as existence is merely the by-product of intestinal gas disturbing the slumbers of a god-like creature whose vagrant dreams can morph into something approaching reality, but which vanish like a popping soap bubble when the god awakes?


Not the answer you're looking for? Browse other questions tagged or ask your own question.