Wait… don’t all eukaryotes have mitochondria, including unicellular ones? I think “Complex single cells unlikely” on the poll is a better fit to your position.
It is worth noting that there are numerous examples of endosymbiosis all over the tree of life and the mitochondrion and plastids aren’t the only ones, just the most successful and most ancient.
There are bacteria that have bacterial endosymbiotes, and I’ve seen electron micrographs of large bacteria with strange uncharacterized archaea hanging off them like tassles. Some animals, mostly insects that drink plant sap, have endosymbiotic bacteria that have had their genomes stripped down to only 150 genes and cannot make their own cellular energy that only exist to make essential amino acids so that the animal does not have to eat them. Large numbers of photosynthetic microbes have taken up eukaryotic green algae as second-order endosymbiotes, or even have taken those organisms up as tertiary endosymbiotes.
EDIT: here’s a chart of the bizarre known history of clades acquiring photosynthesis via known primary, secondary and tertiary endosymbiosis. By the time you are at tertiary endosymbiosis, the plastid has 6 nested membranes and may have some vestigial nuclei between some of them.
It is worth noting that the Cambrian also coincided with the Earth releasing from an ice age that makes everything since look mild, as well as the increase of atmospheric oxygen to levels within an order of magnitude or two of today.
It is also worth noting that there is equivocal evidence of multicellular life before the Cambrian that nobody quite agrees on what it means—things that look like worm-trails in seafloor sediment a billion years old (but that some think could be trails from the motion of giant protists), flat sheets with a distinct center and edge 2 gigayears old, and macroscopic curly fibers two or more gigayears old...
Wait… don’t all eukaryotes have mitochondria, including unicellular ones? I think “Complex single cells unlikely” on the poll is a better fit to your position.
It is worth noting that there are numerous examples of endosymbiosis all over the tree of life and the mitochondrion and plastids aren’t the only ones, just the most successful and most ancient.
There are bacteria that have bacterial endosymbiotes, and I’ve seen electron micrographs of large bacteria with strange uncharacterized archaea hanging off them like tassles. Some animals, mostly insects that drink plant sap, have endosymbiotic bacteria that have had their genomes stripped down to only 150 genes and cannot make their own cellular energy that only exist to make essential amino acids so that the animal does not have to eat them. Large numbers of photosynthetic microbes have taken up eukaryotic green algae as second-order endosymbiotes, or even have taken those organisms up as tertiary endosymbiotes.
EDIT: here’s a chart of the bizarre known history of clades acquiring photosynthesis via known primary, secondary and tertiary endosymbiosis. By the time you are at tertiary endosymbiosis, the plastid has 6 nested membranes and may have some vestigial nuclei between some of them.
Yeah, somewhat. I think what I was getting at by complex multi cellular life is that I think the cambian explosion http://en.m.wikipedia.org/wiki/Cambrian_explosion is rare.
It is worth noting that the Cambrian also coincided with the Earth releasing from an ice age that makes everything since look mild, as well as the increase of atmospheric oxygen to levels within an order of magnitude or two of today.
It is also worth noting that there is equivocal evidence of multicellular life before the Cambrian that nobody quite agrees on what it means—things that look like worm-trails in seafloor sediment a billion years old (but that some think could be trails from the motion of giant protists), flat sheets with a distinct center and edge 2 gigayears old, and macroscopic curly fibers two or more gigayears old...