4 ms·

True they are genetically different but that's not the definition of a 'species'. There is a level of politics in biology over what constitutes a species and w

by ascotan 10y ago

True they are genetically different but that's not the definition of a 'species'. There is a level of politics in biology over what constitutes a species and what does not. Technically a 'species' is something that interbreeds but does not breed with members outside of it's species and mating produces reproductive offspring. (at least this is the old mayr definition that everyone uses) The problem is that neanderthals and humans matings produced viable offspring. So is 'neanderthal' a species or not? The same issue is a problem with the Galapagos finches, which are the holy cows of darwinian genetics. By Mayr's definition they should not be able to interbred and produce viable offspring. However, apparently they can interbreed and therefore are not technically different species. No one in science want's to badmouth the masters, so Darwin's theory of Galapagos finch species will quietly be put back in the Victorian cabinet while we invent a new 'genetics' based theory of 'species' that makes everyone happy. However, life is not easily classified. Viruses? Species? Bacterial plasmid replication? There is a lot of politics in the life sciences. Naming a new species or having your name on a species is a big deal. It reminds me of Cope/Marsh and the dinosaur finds (https://en.wikipedia.org/wiki/Bone_Wars https://en.wikipedia.org/wiki/Bone_Wars) of the early 20th century. They both screwed up the identification of many species so that they could out publish the other and left the mess for future scientists to clean up. My feelings on this is that we still don't have enough evidence about the genetic makeup of humans to really make any conclusions on anything. Example: What is the blood type in the reference sequence for the human genome?? We know that there is A, B, A/B and O which represent 4 different genotypes (an AA sequence, a BB sequence, an AB sequence and a missing sequence from both alleles). If I sequence a neatherthal with blood type A and a human with blood type O, are we genetically divergent?? How can you come to this conclusion unless you know the plasticity of each genome. (i.e. I can't identify a nucleotide change in blood type gene for a type O human because the gene is absent) It looks like most of the research has been on mtDNA which is passed from mother to child. If we can't find a mtDNA match, it might just mean that there is no maternal linage that can be traced back to that sequenced individual. (i.e. all the children of that mother died out at some point) Different species? That's a question for politics imho. I personally think that life shuns classification. BTW sorry for the ramble :0

simonh 10y ago
Then you have ring species[1] that blow a nice big hole in the interbreeding based definitions of species. Species and race are vague terms we use for convenience. That's all. I think keeping them vaguely defined is a feature not a bug, because it could help prevent people assigning too much weight or meaning to them. If people get the idea that race and species can be precisely defined, then maybe they can be measured? Maybe we can use that to derive tests or policies? But trying to precisely define race and species is futile, like trying to put light in a box. I'd rather knowingly and consciously keep the ambiguity, to remind myself that the terminology isn't the reality. [1] https://en.wikipedia.org/wiki/Ring_species https://en.wikipedia.org/wiki/Ring_species
- hyperpallium 10y ago
  One definition of a "market" is people with the same needs who reference each other (i.e. talk to each other). This transmission of information ("word of mouth") is important for marketung [...though perhaps a bit different today, with referencing internet reviews.] Similarly, the definition of species as individuals that breed with each other has importance for transmission of genes. By this rationale, transitive gene transmission makes ring species a "species". A biologist told me that species are defined, not by theoretical interbreeding, but by actual breeding...so that a single species divided somehow in different environments, is now two species, even when no genetic change has occurred. By this strange extrinsic definition, the human races were different species before global travel... and now are one. And that SV hackers who only breed with other SV hackers, are a different species (and the rise in autistism incidence evidences a genetic effect - in a few million years, interbreeding will be impossible!). Similar for classes, the 1% etc.Though there is crossbreeding in practice, so at most these are ring species.
mirimir 10y ago
No, it's just logic. Inclusion of populations in species depends on breeding ability. And there's no way to test that for fossil individuals vs each other or vs modern humans. So they can't be classified as the same species, or part of a species ring.
Stratoscope 10y ago

by ascotan 10y ago

simonh 10y ago

Then you have ring species[1] that blow a nice big hole in the interbreeding based definitions of species. Species and race are vague terms we use for convenience. That's all. I think keeping them vaguely defined is a feature not a bug, because it could help prevent people assigning too much weight or meaning to them. If people get the idea that race and species can be precisely defined, then maybe they can be measured? Maybe we can use that to derive tests or policies? But trying to precisely define race and species is futile, like trying to put light in a box. I'd rather knowingly and consciously keep the ambiguity, to remind myself that the terminology isn't the reality. [1] https://en.wikipedia.org/wiki/Ring_species https://en.wikipedia.org/wiki/Ring_species

hyperpallium 10y ago
One definition of a "market" is people with the same needs who reference each other (i.e. talk to each other). This transmission of information ("word of mouth") is important for marketung [...though perhaps a bit different today, with referencing internet reviews.] Similarly, the definition of species as individuals that breed with each other has importance for transmission of genes. By this rationale, transitive gene transmission makes ring species a "species". A biologist told me that species are defined, not by theoretical interbreeding, but by actual breeding...so that a single species divided somehow in different environments, is now two species, even when no genetic change has occurred. By this strange extrinsic definition, the human races were different species before global travel... and now are one. And that SV hackers who only breed with other SV hackers, are a different species (and the rise in autistism incidence evidences a genetic effect - in a few million years, interbreeding will be impossible!). Similar for classes, the 1% etc.Though there is crossbreeding in practice, so at most these are ring species.

mirimir 10y ago

No, it's just logic. Inclusion of populations in species depends on breeding ability. And there's no way to test that for fossil individuals vs each other or vs modern humans. So they can't be classified as the same species, or part of a species ring.

Stratoscope 10y ago