Tree of Life

On the phylogenetic tree of life on earth, the oldest of the three main branches is that of the Archaea, a class of prokaryote including extremophiles, organisms that inhabit environments far outside the range which is comfortable for humans. For example, in the submarine volcanic environment of Loihi, which erupted violently in 1996, microbial mats have since been found (see picture). The evidence for life on earth dates back to the oldest rocks on earth, namely the Akilia island sediments of West Greenland. Although the evidence in carbon isotopes for life in these particular sediments has been open to question, there is plenty of evidence in other ancient rock sediments which typically date life back 3.55 billion years.

The theory that life originated in space, and was transported to the Earth’s surface from space, is known as panspermia. But if the oldest life on Earth, perhaps as old as Earth, likes hot environments, is there perhaps a different explanation? Astrobiologists such as Lawrence Krauss think that extremophiles will radically alter our understanding of the origins of life.

If there was a Black Hole at the centre of the Earth, would it have anything to tell us about the evolution of life?

8 Responses so far »

  1. 1

    Mahndisa S. Rigmaiden said,

    10 06 06

    Good read Kea. I always have been intrigued with the panspermia hypothesis, but it could be that panspermia occured for carbon based life forms, but maybe not for extremophiles. The reason why I say this is that organic molecules like ethylene glycol have been found inspace near dust clouds. And I can only imagine a comet or a meteor with some ethylene glycol or some of other sugar alcohol and mixing with the primordial goop that was Earth all those years ago could have radically altered what life could be right now.

    I read something about the early atmosphere of Earth and how it provided a habitat for some organisms to fluorish while others hadn’t a chance. See here. Indeed the Early Earth had a lot of Hydrogen in its atmosphere. Panspermia sounds better and better each day to me…

    Good post:)

  2. 2

    Kea said,

    Hi Mahndisa!

    Good points. Panspermia certainly has good evidence going for it.

  3. 3

    Bill Lama said,

    Dear Kea,
    Thank you for visiting my blog. I’ll respond to your comments there and hope to keep the conversation going.

    I’m a big supporter of women in science and engineering and have had the good fortune to be able to help many women enter the field (during my college teaching days) and advance up the corporate ladder (during my time in management). All my experience and all the cases I’m aware of have been just the opposite. In academia and in industry we actively recruited women (and minorities) and would never think of discouraging them.

    I’ll be exploring your blog. Good luck.

  4. 4

    CarlBrannen said,

    I haven’t been in academia in a good long time and even then I was only a graduate student and did not have a good view of the culling process other than grades and tests.

    But I can tell you that the easiest job interview I ever had was one at a company where I realized that all the people I interviewed with were fat middle aged male engineers who cared about stocks and electronics. I fit right in.

    If I were in person trying to fit into a situation where my “type” was kind of rare, I’d spend a little time adopting the proper camoflage. And I’ve done this myself often enough.

    Back when I ran pinball machines in bars, I taught myself sports so that I would fit in with the bar owners. I wouldn’t advise this; sports are a sort of male equivalent of those interminable daytime television shows. But no matter how bad a team is, they just keep going and going and going. No matter how badly one team defeats another, they meet again over and over. And despite this, if you study it, it can be quite addicting.

    Humans are social (or pack) animals and have to be approached carefully.

  5. 5

    Kea said,

    Thanks for visiting, guys! Bill, your world sounds nice, but to me it’s a fairy tale. In my experience, there are some women who have managed to make the most of things, like you say. Then there are a whole lot more…

  6. 6

    Kea said,


    Yeah! Unfortunately I am afflicted with a low social intelligence, and when I try to be clever it usually backfires.

  7. 7

    L. Riofrio said,

    There is a good chance we will find extremophiles on other planets. We have found bacteria at great depths in the Earth. It could have begun here or migrated via Ni-Fe asteroids that contributed to Earth’s core. Iron itself originated in supernova explosions many light-years away.

    Wherever it began, life could have found a first home within the planet, living off Earth’s internal heat. From there is could have migrated to the seas before crawling on land.

    Male scientists are allowed to have low social skills, be absent-minded and disagree with one another. Women deserve the same rights. Sometimes the shy people are the smartest. Kea, this is yet another fascinating post.

  8. 8

    CarlBrannen said,

    Having spent way too much time with engineers and scientists, I didn’t realize how low their social skills were until I spent a few weeks at at Pilchuck with glass makers (who are a mix of artists and craftspeople).

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