Like say Monkeys(not true of course) or Lemurs(probably not true).
What species of animal looks the same from hundreds of thousands of years, or has adapted thru evolution the least?
As a WAG, I’d say shrews, moles and the like.
I read recently that the opossum is pretty much the same as it was thousands of years ago. I’ll try and find more on it.
AFAIK, any animal that practices asexual reproduction is unlikely to evolve at all. Evolution occurs when errors (technically known as mutations) occur in the copying of DNA from two sexual partners to the DNA of their offspring. This doesn’t occur in asexual reproduction - the DNA of the single ‘parent’ is the same as the DNA of the two ‘offspring’ - so greenfly, earthworms and other asexual creatures don’t evolve (and are effectively, for the same reason, clones).
(My terminology is a bit vague, hopefully some professional biologist will come along and add the proper jargon to the above,
& perhaps even fill in the blanks about how earthworms & greenfly got as far as they did.)
No, the DNA of asexually reproducing organisms can still mutate and the mutations can be favourable or not and thus selected or not - this is why we have antibiotic-resistant pathogens.
BTW, Earthworms reproduce sexually; they are hermaphrodites(both male and female), but they pair up and exchange gametes. Aphids can reproduce parthenogenetically (females can clone themselves), but they don’t exclusively do so.
Additionally, the biggest advantage of sexual reproduction is that it apparently minimizes bad mutations and enhances good ones. I have no idea how this works, I just read it in the news.
Can we just accept that mammals do reproduce sexually?
Yes, it would seem that (natural)parthenogenesis in mammals is either exceptionally rare, or entirely absent. (As Cecil says, there was that one time though…)
Mets fans?
Sorry - couldn’t resist…
The most primitive extant mamals are the 3 species of monotremes: the platypus, the short beaked echidna and the long beaked echidna. These guys still lay eggs.
You beat me to it. That was my response precisely.
Let’s clear something up. It’s really incorrect to say that one anminal is “less evolved” than other animals. We all trace our ancestors back to primitive life forms that existed billions of years ago. Monkeys are not “less” evolved than humans. They’ve simply evolved in different ways. In fact, one could argue that smaller, faster reproducing animals are more evolved than humans since they’ve had more generations to reproduce and to acquire mutations. Evolution is not a process that is directed at producing humans, with the other animals falling by the wayside as failed experiments.
Having said that, it appears that shrews are the extant animals that most physically resemeble the early mammals.
Des: Didn’t we go thru this whole deal just 2 days ago in this thread about monotremes not necessarily being precursors of placental or marsupial mammals?
Just because a species has been around for millions of years doesn’t mean it has stopped evolving. Natural selection continues to occur even in the absence of any apparent change in the appearance of a species. I would argue that the amount of time a species has spent evolving should date from the time that species first appeared. In which case, Homo sapiens sapiens would qualify, having emerged only about 120,000 years ago.
What’s your problem, John Mace. How do you read “most primitive” as meaning “necessarily being precursors”?
Thats amazing.
Guys? Laying eggs!
Transgendered oviparity!
Whoda thunk?
I think his point is that if monotremes are not precursors of placental mammals, there’s no reason to assume they’re more “primitive”. If they evolved on a seperate track from placental and marsupial mammals, they could have done so at anytime.
“the biggest advantage of sexual reproduction is that it apparently minimizes bad mutations and enhances good ones.”
I can think of several other “advantages” to sexual reproduction.
That would render the whole question meaningless.
To say that no extant organism is more primitive than any other isn’t a terribly helpful idea, either.
I would say that a genetically engineered Myxini, which I could definitely say only evolved last Wednesday when it was created in a lab, was still a more primitive organism than any Teleost.
Ding, ding, ding! We have a winner!
Every mammal, indeed, every organism alive today has had the same “amount of evolving” as every other organism. Evolution never stops.