Why does evolution have to include branching?

Question

Is the branching concept implicit in the idea? Why it is not plausible that each being/creature evolved from the primordial soup as its unique self without any branching? Rather than a branching tree concept, why is not something like individual grass shoots coming from the mud concept as robust an explanation? Another image would be a seed concept. Each being, whatever it was as it emerged from the primordial soup, like a seed was a primitive form of what we see today, but like a seed, it evolves into a new form of itself in stages. Millions of beings lost out in the competition and didn’t make it and died out. Could this explain ecological niches as well for beings that evolved in relationship to each other?

Could the evidence be explained this way just as plausibly as a branching pattern? Obviously, I’m not a scientist, but I am sincere and extremely curious. I’d appreciate being taken seriously and not mocked – you can do that off-screen.

Answer 1

Both situations have occurred. There are creatures that have evolved very little since the beginning of life on Earth. But branching is inevitable, since different environments and their associated pressures exist to "mould" evolution. You concept of blades of grass would be valid if all the individuals within a group were the same, but they are not, and have different chances of survival in different circumstances. These will then give rise to more blades of grass, similar to themselves, but different to those that didn't make it, and different to others of the same species that also survived. This is the origin of diversity and of branching. Over millions of years, it would be inevitable that branching occurred, less in stable environments, more in harsh environments.
A good book for examining this branching is probably Richard Dawkin's "The Ancestor's Tale".

Happy learning.

Answer 2

Well, without branching evolution could only produce one species. So since there are millions of species on the planet, this would mean that evolution would have to have occurred milions of times from the ooze to a nwe multicellular creature.

That kind of evolution just would not explain the evidence.

For example, it is extremely unlikely that one path from the primordial ooze to multicellular vertebrate would produce a horse, while another completely independent path all the way from the primordial ooze would produce a donkey. It is a far simpler explanation that the horse and donkey are two branches from the same ancestor.

But a far more compelling case is the fact that the horse and donkey share common DNA ... literally entire segments of DNA that are absolutely identical between the two species. That is clear evidence that the two evolved from one ancestor, even though the two are now two different species and cannot interbreed.

In fact *ALL* living species share DNA. The closer they are in the cladistic location (their classification) the more DNA they share.

Even the fact that they all *have* DNA (the same type of molecule, with the same rotation of the double-helix, with the same list of amino acids etc. etc.) is evidence of common ancestry. There is absolutely no reason why other types of DNA (e.g. one with a double-helix that turned to the left instead of the right) could not be the basis of other life forms ... but there are no other such life forms.

Common descent through branching is just there throughout the evidence.

Answer 3

Evolutionary biologists and phylogenists generally take the principal of parsimony to heart when testing evolutionary trees (i say trees because this is the general consensus within the field). The principal of parsimony is basically just "simpler is better." When applied to evolution, it means that the best tree is going to be the one in which each branch requires the least number of changes to have occurred.

If all species arose as is from the "primordial soup," which contained only unicellular beings, then each one would have had to undergo uncountable numbers of changes all at once to arise like that. With the tree scenario, the organisms with the least number of changes would be at the bottom and other, slightly more complex organisms would have used these organisms as a baseline, deriving the least number of changes from these others. More organisms, still would have derived from these, and so on.

I hope that answers your question and wasn't too garbled.

Answer 4

"Branching" is simply a phenomenon that results from our propensity to group large numbers of individuals into species, genera, classes, etc. Yes, every individual could, in theory, trace a lineage that goes back to the origin of life, but we do not have the scientific power to investigate every single person's evolutionary lineage (heck, we don't even have enough power to do it for most species).

Instead, grouping individuals into species by "lumping" them together is a powerful tool that allows us to investigate and describe phenomena that would otherwise be too detailed or complicated to do so otherwise. We lose some detail, but in the end, this loss of information is miniscule compared to the amount gained.

Of course, we have to be careful about "lumping" in general, because sometimes the loss of information is NOT miniscule compared to that gained. Likewise, "splitting" often times gains us additional information, but we have to be careful not to introduce more noise than information gained.

In practice, using taxonomy has been a powerful tool in describing and studying biology and evolution. It DOES break down in some very specific circumstances, but in general it does work well.

Unfortunately, trying to use an intuitive understanding of "lumping" sometimes gives us inaccurate or unhelpful conclusions. A common example is how we think of infections--we think of taking "antibiotics" to kill the "bacteria." We get tripped up, however, when we think the "bacteria" have been killed, so we stop taking the antibiotics. In reality, of course, the "bacteria" are actually millions or billions of individuals, all with different responses to medications (some with resistances).

Answer 5

well, the main evidence we have against that hypothesis is in the genes. Similar genetics between species point to common ancestors they "branched" off of. There are even parts of our DNA that are sort of unused "junk" DNA that we share with our related species. Evidence of genetic modification to old diseases stay with our DNA and can be seen in other apes. But there are some species that are further away from their "relatives" so it can't be said for sure if they share a common ancestry.

Answer 6

"Branching" is just a visual metaphor for the results of speciation. An individual species will branch from its parent species when they become so much different that they are unable to interbreed. If the root of the new species was at the "base" of the tree, it would imply that the new species had arisen independently of its parent.