Because if we’re more closely rather than less closely related there’s a greater chance such exo-biotes (alien living things) could adapt to or survive & reproduce inside our bodies.

If, for instance, we’re both carbon-&-water, DNA-RNA sugar & light feeding organisms rather than say us being carbon-&-water, DNA-RNA sugar & light feeding organisms but them being, say, LiNeFlHg* based silicate & gamma ray feeding organisms clearly the chances of them being compatible and able to cause disease(s) in us is vastly greater.
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* LiNeFlHg -based = Lithium Neon Fluorine Mercury based living creatures! An unlikely blend of exotic elements for life because of rareity and less reactive / more reactive chemical factors I know. I’m not postulating such alternative life merely a hypothetical example but …
a-n-y-w-a-y … You get my point I hope.

“I was wondering: Could it be dangerous to revive microbes from millions of years ago to which humans have never been exposed? I would think that this would have to be done with very careful control to remove the the risk of the microbes leaving the laboratory.”

It would be I’d expect.

But the danger is probbaly unlikely as humans and such microbes (nanobes /virii) would (most likely) be so vastly different as to be just too incompatible for creating diseases in each other.

Parasites – even virii – depend on adapting to and living within (& exploiting for reproduction) – their hosts – it seems most probable alien organisms will be incapable of doing this.

Panspermia in which life is derived from a common source may if true make us more vulnerable. Hoyle is a pretty smart bloke and a good writer but I remain unconvinced if intrigued by his arguments – I have read his book (co-written with Wickramasinghe – spelling?) many, many years ago.

Venus had a nice protective atmosphere, extra heat and warmth – and oceans.

Mars had a nicely warm if cooling surface, thin but better than todays atmosphere with oceans, lakes and glaciers plus a shallow gravity well allowing material to be blasted off into space releatively easily.

Erah had suffered a mammoth impact (forming our Moon) was molten or just highly geologically active with a thick poisonous atmosphere, deep gravity well and oceans.

Later on, mind you, Earth froze into an enormous snowball, Mars lost its air and activity and chilled whilst Venus overheated & turned into a toxic pressure-cooker. Earth recovered – its planetary neighbours well … didn’t.

But all three of those worlds could have been the origin for simple life living in _very_ different conditions from today.

Perhaps all three of them were.

I think comets *may* have carried ammino acids and protein-carbon chains to Earth. I think its likely life _could’ve_ emigratedfrommars to Earth via meterorite. Life *could’ve* begun in molecular clouds on small grains of dust drifting in the void.

All speculative and plausible rather than proven but interesting.

& wasn’t Svante Arrhenius or somebody like him (spelling?) the originator of that panspermia idea – as well as first noting the Greenhouse effect?

I was wondering: Could it be dangerous to revive microbes from millions of years ago to which humans have never been exposed? I would think that this would have to be done with very careful control to remove the the risk of the microbes leaving the laboratory.

Oh man, I wish I knew that was on!

Don’t suppose the programme can be watched online? Not that I’ll be able to watch it ’till I get my net @ home fixed…

Panspermia is one big cop out

Q “So how did life arise on the Earth”
A “It came from another planet but managed to get here by a comet”
Q “So how did it arise there then”
A“Oh it didn’t, it came from another planet and was lanted on that planet”
Qgives up as he can see where this is headed

All you do is move the question back up the line of how did life come into being.

We have been working on this for years and still have never got anywhere near something living. To say it was planted from somewhere else is ducking the issue.