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Like other animals, why don't humans have species & breeds ?
Even my pet dog is one type of breed, but we (humans) lack breeds & species? What is the main reason?

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    $\begingroup$ Related: Do humans have enough biological differences to be grouped into races or subspecies? $\endgroup$
    – fileunderwater
    Commented Nov 21, 2014 at 12:38
  • $\begingroup$ You could ask any question of the kind Why don't <insert species> have species and breeds while <insert non-species taxon> do? such as for example Why don't tigers have species and breeds while dolphins do? The question mainly reveal your intuition that we should eventually talk about human breeds when talking about ethical groups. $\endgroup$
    – Remi.b
    Commented Dec 27, 2016 at 8:28
  • $\begingroup$ To improve your understanding of the concept of species, you should have a look at How could humans have interbred with Neanderthals if we're a different species? $\endgroup$
    – Remi.b
    Commented Dec 27, 2016 at 8:32
  • $\begingroup$ There are a lot of genera with only one species under it. I guess you want to find evidences that human is very special. But unfortunately we are not. $\endgroup$
    – High GPA
    Commented Mar 22, 2022 at 6:38
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    $\begingroup$ We do, we just call them races, you have black people, white people, Far Asian people, near Asian people, Indians, Eskimos $\endgroup$
    – Dave
    Commented Jan 6 at 5:38

2 Answers 2

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If you with 'humans' refer to our genus Homo (which is often the case), we do have multiple species, see wikipedia for an overview. The difference to many other organism groups is just that all species except Homo sapiens are extinct.

Also, taxonomic ranks below the species level - such as breed, subspecies, population and race - are very poorly definined and are usually used in different ways in different taxonomic groups. It is therefore difficult to draw one-to-one comparisons between these types of ranks across taxonomic groups. It is even relatively meaningless to compare e.g. taxonomic families between taxonomic orders, since they are used in such different ways, and compared to ranks below the species level taxonomic 'order' and 'family' have much clearer definitions.

However, if you with breeds of dogs are referring to distict phenotypes (which is basically what they are), you can easily see that some human populations also have distict phenotypes, so in this sense they are similar.

The reason why the concept of human races is largely obsolete and controversial (along with breeds) is clearly our human collective history of racism, nazism and eugenics.

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  • $\begingroup$ how come all species of human extinct except homo sapiens why? $\endgroup$
    – user10246
    Commented Nov 22, 2014 at 2:33
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    $\begingroup$ @johnson316 A current hypothesis is that Homo sapiens was a major reason for the extinction of Neanderthals (and maybe other human species as well) - see e.g. this popular summary. $\endgroup$
    – fileunderwater
    Commented Nov 22, 2014 at 10:11
  • $\begingroup$ @johnson316 You might find answers to this question interesting as well: Why Did 6 Great Ape Species Survive But Only 1 Hominid Species? $\endgroup$
    – fileunderwater
    Commented Dec 19, 2014 at 14:49
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    $\begingroup$ @johnson316 Chris Stringer's book Lone Survivors is a both beautiful and informative read, and deals precisely with your question. $\endgroup$
    – Yisela
    Commented Jan 15, 2016 at 20:39
  • $\begingroup$ the concept of human races is also really hard to mesh modern cladistic classifications, genetic diviersity ussually varies more within a race than between them, meaning they don't have a strong biological value. $\endgroup$
    – John
    Commented Oct 25 at 1:00
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  • Humanity has limited genetic variability.

    • This is caused by humans being a new species, only 200,000 year old.
    • Went through a genetic bottle neck 50,000—100,000 years ago. Reducing the human population to 3,000—10,000 reproducing individuals
    • Only recently managed to expand its range out of Africa ~60,000 year ago.

  • Humans are very mobile.

    • The gypsies originate from India. And have been touring Europe for the past 1000 years.
    • The population of Madagascar is a mix population of 50% African and 50% South east Asia which arrive in Madagascar some 1600 year ago.
    • Romans... well moving people around Europe and Africa was their thing too.

  • Humans love making love.

    You can only get a breed if you have barrier... but there are few barriers that can stop human lust. So our genes get mixed a lot. Even when we don't think they should not.

TLDR: Our initial genetic variability is limited for several reasons. Not enough time has passed to develop that variability. We are also too mobile for distance to be a good barrier... and phenotype changes which do arise does not in anyway dissuade humans as a whole from exchanging bodily fluids and gametes.

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