rationalskepticism.org

Latimeria wrote:

ughaibu wrote:Why?

You seem to be thinking of horizontal gene transfer only in terms of its functionality within extant biological species descended from a common ancestor with a common genetic code.

Not at all, as common descent is the matter under dispute, in the subject of this thread, I make no assumptions about it.

halucigenia wrote:It would be possible for the tree of life to have anastomosing trunk or branch system if you include HGT.
But not separate points of origin as if it had aerial roots i.e. separate abiogeneses (is that a word?) producing different heritable systems that then merge.

But this is exactly the belief for which I'm asking justification, there's no point in just repeating it.
The claim made:

Latimeria wrote:If it arose entirely separately, it seems to me absurdly unlikely that any horizontal gene transfer could even happen.

is rather strong. It implies that given the occurrence of horizontal gene transfer, anything but the universal common ancestor hypothesis can be discarded as "absurdly unlikely". But this is very odd, as horizontal gene transfer has been cited in support of hypotheses which compete with UCA. So it seems unlikely to me that there is an argument from probability by which an absurdity can be established. Of course, such an argument would be interesting, however, neither Calilasseia nor Latimeria have given such an argument, in fact Latimeria states

Latimeria wrote:The genetic code as we know it is nearly universal, but not entirely

and

Latimeria wrote:we really don’t know enough about abiogenesis to even suggest that a process which allowed a self-organizing system to create life would even be likely to do it again in a manner similar enough for HGT to have any meaning.