It's barely been a week since the existence of a whole new kingdom of life was confirmed (https://www.nature.com/articles/s41586-018-0708-8), certainly an exciting time for biologists. Must be tough even keeping up with the latest developments.
If we're talking about single-celled organisms, it's quite possible that there are hundreds of "kingdoms" living among us. The trend to abandon the Linnaean classificaton is quite prominent among those analyzing macroscopic organisms. But among those working with microscopic organisms, I've come across some of them abandoning the tree of life itself. My mind was blown when I watched the discussion between Dawkins and Venter.
The last article is extremely misleading. It is true that there are variations of the genetic code. (Wikipedia says 32, including the usual genetic code that we have. https://en.wikipedia.org/wiki/List_of_genetic_codes )
So the easiest explanation is that the genetic code evolved from a genetic code ancestor. Moreover, our genetic code is probably not the original code. IIRC the guess is that initially it has only 16 slots. These slots are visible as some big squares in the curren table, but some of these slots are divided now.
Most of the time a change in the genetic code is catastrophic, so it's not easy to change it. But it may be possible if it changes one aminoacidic by a similar one, or if you are extremely lucky. In the table all the changes are in mitochondria/bacteria/archaea, not in animals or plants. Since they are small, they have bigger numbers and faster generations, so they have a bigger chance of a lucky random mutation.
In particular, 12 of the 32 genetic codes in the list are variations in mitochondrial code. All the mitocondria are very similar. The incorporation of mitocondrial was a very strange lucky event. Nobody think that the 12 variants of mitochondria appear independently, each one in its own tree of life, and were absorbed later independently.
I don't like the "gotcha, Dawkins" stance of the article, but apart from that, it looks like they were doing their best to fill in the gaps that Venter left. If memory serves me right, this discussion panel met shortly after Venter's group announced the creation of a life form with a completely synthetic genome. Venter had adequately proven his credentials by that point, and so the panel deferred to his expertise.
Given that the likes of Dawkins could not follow along, Venter certainly did a poor job of communicating the ideas.
Is it known what killed off mammoths? Was it human hunters killing them of or some natural cause? Something like climate change that caused them to not have enough food?
Consider that mammoth populations survived past the ice age in places that humans did not live, mostly islands north of Siberia. Now consider that those mammoths were quickly extinguished as soon as humans touched foot on those islands.
This was a giant mammal that coexisted with dinosaurs. I had always thought that mammals appeared during the age of dinosaurs, but they were all tiny mouse-sized mammals.
For comparison, see the graph in the same page https://en.wikipedia.org/wiki/Evolution_of_mammals#The_ances... . Here is the split between reptiles/dinosaurs/birds and the ancestors of mammals in the second branching. (You can "glue" the other graphic in the lowest branch of this graphic, but I'm not sure if they have a comparable level of detail.)
The ones that survived the Giant Frying were mouse-sized, but bigger ones existed before then, even though they might look mouse-sized to a passing brontosaurus.
Imagine the latest common ancestor of all mammals i.e. the last individual that all mammals are related to. The species in the article would not be an N-th degree child of this individual, but it would be an N-th degree cousin of this individual.
Well, the article keeps saying "mammal relatives". They're really just saying it was a cynodont. Mammals are the only remaining cynodonts, but there used to be other kinds. I'm pretty sure this doesn't challenge the idea that, at the time, mammals were all still small shrew-like jobbies. For one (totally not a biologist, but I do spend way too much time at museums) its skull doesn't really look mammalian to me.
Not quite mammals but mammal-like reptiles. They're related to mammals but not our direct ancestors, more like aunts and uncles in the evolutionary family tree.
