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A Near-Term Read on Life in the Galaxy

Although he doesn’t post nearly as often as some of us would like, Caleb Scharf’s Life, Unbounded site is always worth reading. Scharf, author of the textbook Extrasolar Planets and Astrobiology (University Science Books, 2008) is the director of the Columbia University Astrobiology Center. As such, he’s positioned to offer valuable insights into our investigations of the forms life might take on other worlds. Not long ago he wrote a fascinating post for Scientific American on a statistical approach to astrobiology, a timely idea as we discuss ongoing missions like Kepler and proposed space telescopes like WFIRST.

Natural Selection on a Galactic Scale

Scharf’s latest is a quick take on panspermia, the idea that viable organisms may be exchanged between planets as various early impacts spread debris through a planetary system. We know that surface material moves continually between the rocky moons and planets of our own system, and we’ve also come to understand that microbial organisms of great hardiness might survive such extreme journeys, even though they involve millions of years of exposure to interplanetary and even interstellar space. Life may indeed be seeded on a galactic level.

But if this is the case, what about the role of natural selection? Scharf writes:

Although it’s a complex problem, it seems likely that life driven by cosmic dispersal will end up being completely dominated by the super-hardy, spore-forming, radiation resistant, rock-eating (endolithic) type of critters. There will be no advantage to a particularly diverse gene pool. Billions of years of galactic transferral will have whittled it down to only the most indelicate and non-fussy microbes – super efficient, super persistent, and ubiquitous – the galactic top dogs.

All of this would fit with what we see on Earth, for we know about numerous organisms in extreme environments here that do indeed survive under conditions most living things would consider hostile. Scharf’s point, though, is that if panspermia is true on a galactic level, then tough organisms like these should be just about everywhere. As our robotic probes grow in sophistication, they should start finding life’s tenacious foothold throughout the Solar System, from the ancient seabeds of Mars to the smog-choked surface of Titan. A galactic panspermia would know no favorites, and it has had billions of years to work.

Galactic panspermia, in other words, is going to make itself apparent in the not distant future. If we find that this is not the case, that life doesn’t pop up just about everywhere we look, then the case for panspermia at this level is vastly weakened, although we can still see a role for panspermia between planets. The larger question of life around other stars, in that case, will remain as intractable as it does today, and will require our most advanced instrumentation to detect in the form of atmospheric biomarkers on Earth-like planets near enough to study.

From Sagan to Drake

All of which reminds me of a recent interview with Seth Shostak. Asked about Carl Sagan’s estimate that there might be one million intelligent species in the galaxy and Frank Drake’s speculation that the number was closer to 10,000, Shostak comes down on the side of Drake, noting that if 3 percent of the solar systems in the Milky Way have Earth-like planets, then 10 billion such planets must exist. Assume just one in a million to have intelligent life and you still end up with 10,000 civilizations. Kepler will let us tighten these numbers within a few years.

Shostak takes note of the debates he has had with Rare Earth author Peter Ward, who argues in his book with Donald Brownlee that intelligent life must be scarce due to the huge number of factors — Jupiter-like planets, a nearby moon, the tight parameters of habitable zones — that would make it possible. Shostak:

I’m not at all convinced that moons are needed to support life. Without the moon, the tides would be different and the poles would migrate every so often. But that wouldn’t wipe out life. Regarding gravity, there are already two planets with earthlike gravity in our solar system, and even Mars could probably have supported life earlier in its history (and maybe even today). And we are now fairly certain that Jupiter sized planets are commonplace – we have already located hundreds of them. So I just don’t find the argument that complex life must be rare in the galaxy to be compelling.

The encouraging thing about these discussions is that we are dealing with issues about which we will have preliminary answers within a matter of years. Kepler will be able to give us statistical answers about the prevalence of Earth-like worlds in the galaxy, and using Scharf’s reasoning, we can draw extrapolations on the likelihood of panspermia based on what we find in our own system fairly soon, just as long as it takes to get complex robotics to environments like Europa.

True terrestrial planet hunter spacecraft — the kind that can make spectroscopic analyses of exoplanet atmospheres on worlds this small — are at least a decade and perhaps much more away depending on funding issues, but they represent logical extrapolations of near-term technology. In 25 years, we will have not just a philosophical view of life in the universe but a practical knowledge based on data that can tell us whether we’re likely to be alone or simply one among many galactic species.


Comments on this entry are closed.

  • Bob Steinke August 20, 2010, 12:13

    I wonder if Scharf has considered the time scale for galactic panspermia. A directed, goal-oriented colonization program by intelligent beings would take at least millions of years to colonize the whole galaxy. The random walk of microbes on impact ejecta would take many orders of magnitude longer. Maybe longer than the age of the galaxy. Certainly, if our solar system was seeded with microbes from another solar system you would expect to find them everywhere in our solar system. But if we don’t find them it doesn’t mean galactic panspermia isn’t occuring elsewhere in the galaxy and just hasn’t gotten here yet.

  • Mike August 20, 2010, 13:37

    That was an interesting post alright.
    If some microbes,(or something like microbes), are hardy enough to survive drifting for tens of millions of years through interstellar space,survive re-entry and still be viable on a planet’s surface they would be tough little buggers indeed!
    And if they are that tough perhaps traces or remnants of them could still be found on sterile worlds that they would finally have died on. Consider the Moon. If these little bugs are drifting everywhere perhaps a closer look at the Apollo moon rock samples is in order. But I think the moon rocks have already been very closely studied and nothing has been announced so far about possible biological traces.
    What, if anything does that suggest about the galactic panspermia concept?

  • philw1776 August 20, 2010, 14:53

    Shostak comes down on the side of Drake, noting that if 3 percent of the solar systems in the Milky Way have Earth-like planets, then 10 billion such planets must exist. Assume just one in a million to have intelligent life and you still end up with 10,000 civilizations. Kepler will let us tighten these numbers within a few years.

    I take serious issue with unscientific ‘advocates’ like Shostak. No matter WHAT % number Kepler gives us for Earthlike planets, no matter how accurate it is, and it won’t be, that # is dwarfed in significance by the totally unscientific swag “one in a million have intelligent life”. Most of us space cadets do our own Drake equation math but it cannot be taken seriously. We have NO data on any ET life whatsoever and do not understand evolutional probabilities and whatever ‘laws’ govern the probabilities and predelictions of intelligences to make such assertions. He’s simply bandwagoneering for his SETI efforts under the false guise of science expressed as numerics.

  • NS August 20, 2010, 15:23

    It’s not really an either/or thing. Life on some worlds may be the result of panspermia, on others it may develop locally, maybe even out-competing the panspermia organisms if/when they arrive.

    Also, life does not necessarily equal intelligence:


  • Tulse August 20, 2010, 16:48

    Even if there are organisms that can survive for thousands or millions of years in space, that still doesn’t solve the problem of how to get them into space to begin with. One might presume that meteor impacts might pry loose some microorganisms from a colonized planetary surface with sufficient force that gives them escape velocity without frying them, but even so, the speed they will travel at will be extremely slow for galactic colonization purposes. If I’m calculating correctly, escape velocity for the earth (ignoring atmospheric friction) is approximately 0.000037 c, so an object travelling at that speed for a billion years will only get about 1/3 across the Milky Way. It seems to me extremely unlikely that one will end up with ubiquitous colonization of the galaxy via this method.

  • andy August 20, 2010, 17:56

    I’m going to have to agree with philw1776 here, this seems like a whole lot of handwaving and bad biology. Especially that point about “no advantage to a particularly diverse gene-pool” and that the gene pool would have been whittled down, sounds like a load of rubbish to me: one could equally well make the same argument that billions of years of natural selection ought to have produced hyper-efficient life forms here on Earth. Seems to be a misconception that evolution is directed to produce the best solution: this is not the case, evolution produces things that work well enough.

  • Enzo August 20, 2010, 19:33

    “True terrestrial planet hunter spacecraft — the kind that can make spectroscopic analyses of exoplanet atmospheres on worlds this small — are at least a decade and perhaps much more away depending on funding issues”

    Not before well into the 30s if you are following the debate on the Decadal Survey:

    SIM is the only short term mission that would have found a earth sized planet amongst the 60 closest stars and it’s dead.
    I have not heard anything about the occulter from Webster Cash either in years. His site has news only up to 2008.
    Microlensing and Kepler will give us some very important statistics but they will not characterize our neighborhood.

    Gaia will at least find every Jupiter with orbital period between 1.5 and 9 years within 150 ly and provide a wealth of great information about 1 billion stars :

    This probably means it’ll find some Neptunes for closer stars.
    The mission finishes nominally in 2017, just when some of the gigantic telescopes are coming online : I hope for some direct imaging of Gaia results.

  • Enzo August 20, 2010, 19:34

    “Not before well into the 30s ”

    I meant the 20s, but i maybe unfortunately right anyway :-(

  • walter b marvin August 20, 2010, 22:14

    I think the guys that say we can’t know the fraction of intelligent life species there might be in our galaxy are missing one crutial piece of logic: The real question is not if intelligent life will occur, but when intelligent life will occur. Intelligence is clearly a substantial survival advantage. Our experience is that intelligence of various kinds has been a critical part of survival of many species, but that self awareness is a rather recent development. If one assumes our experience is average, and adds in the formation and cooling time for the planet, the time for life itself to develop, and our information sphere of announcement, then the time from planetary inception to the possibility of intelligent life detection from any particular vantage point might be a good fraction of the galaxy’s lifetime. This type of analysis might be a good starting point for a more substantial number.

  • Stan August 20, 2010, 23:40

    I like the idea of galactic panspermia. This is the first time I’ve heard of it and, as excited as I was at first, I soon found it difficult to imagine happening in reality. The problem I have with it is the image of a great wind of bacteria sweeping through the galaxy, settling on every bit of a planet in every star system they breeze through. It seems more likely that it would be just the opposite. Say a very large number are sent into space on debree from a very large asteroid hitting a planet. In terms of the distant stars in the galaxy, that is a point source. Each of those bits of debree will move farther away from all the others the farther they get from the planet, so that by the time they reach even the first star system they will be so far apart that I would be very surprised if more than one actually went through the star system. Certainly not a breeze of them. And when they get to the star system even further out, the chances of even one going through it are extremely small. To say nothing about landing on one of the tiny planets in it. It seems to me that we would be much more likely to get life evolving from scratch on each of these planets than spreading by panspermia.

  • Caleb Scharf August 21, 2010, 13:19

    Thanks for pointing to my post. I too wish I could add more regularly, the pressures of other activities often take a grip. All good comments from people. Totally agree that my blithe statement about how the evolution of panspermia-suitable organisms is a gross simplification. Nonetheless, the demands of this type of dispersal are sufficiently extreme that I think it’d be fair to say this would place enormous selection pressure on the populations of organisms in question. Evolution indeed pushes for what works, not necessarily what’s optimal, but in this case the requirements are pretty darn steep.

    Another good point about ejecta velocities and how you’d actually spread galaxy-wide in a mere ten billion years. The kind of velocities we’re talking about for spalled ejecta can reach into the few 10’s of km/sec range in the case of the Earth. Depending on planetary configurations these are getting towards system escape requirements, but it’s still a long trip to the next star. Having said that, over a few billion years we’re talking about billions of ejecta the size of a baseball (roughly speaking), that’s a lot of stuff spewing out into the differential motion of the Galaxy – and we live in a dynamically ‘quiet’ type of planetary system.

    I also have great skepticism about panspermia beyond exchange between local planets – but I thought this was an interesting topic to try to ruffle up a little !

  • NS August 21, 2010, 17:50

    It’s been pointed out here before that the conditions for life to appear may be much more restrictive than the conditions under which it can survive once it develops. So a possible scenario is for life to get started in a highly favorable environment (e.g. Earth or early Mars) and spread out from there (panspermia) to more hostile areas in the stellar system. I have to say though I think interstellar panspermia is a lot less likely.

  • Brollen August 21, 2010, 17:57

    I am a mere novice in these things and I truly enjoy reading this website and pondering all things of a cosmological nature.

    I have a question concerning Dark Energy/Matter:

    If Dark Energy/Matter exerts such a strongly negative pressure to counter-act gravity why would we think that Dark Energy is at play in Abell’s Cluster? Wouldn’t the light that is bent be instead scattered in “negative” directions which we could not see or that wouldn’t even reach us?

    The comments under the image – “The massive gravitational force of the dark matter (shown in blue) in giant galaxy cluster Abell 1689 bends the light from distant background galaxies, giving astronomers clues to the nature of dark energy” – make it sound like dark matter behaves like normal matter when the current assumptions are that it is a repulsive and opposite-effecting force.


  • Paul Gilster August 21, 2010, 18:14

    Brollen, I think you’re confusing dark matter and dark energy. What the image comment says is that the dark matter associated with Abell 1689 causes gravitational lensing. As far as we know, this is the case. Dark matter has no repulsive force — there you’re talking about dark energy, a different thing altogether. In other words, the one (dark matter) can be useful as we study the other (dark energy).

    Hope this clarifies, and glad to have you as a Centauri Dreams reader!

  • Tulse August 22, 2010, 1:12

    “Intelligence is clearly a substantial survival advantage.”

    I’m not sure that’s true. Over half the biomass of this planet is composed of unicellular organisms, which existed for billions of years prior to anything more complex. And while intelligence has certainly been beneficial to human survival, it also threatens it, as we are the only species on the planet with the capability to wipe out most complex forms of life on earth.

    In the end, it is extremely hard to over-rate the survival advantage of being unicellular.

  • Ronald August 22, 2010, 6:29

    In addition to Tulse and Caleb Scharf;

    Besides the limited velocities of any potentially life-bearing ejecta, I think there is also the simple and obvious, but apparently overlooked issue of the very, very minute chance of any such object actually ever hitting a potentially suitable planet:
    I think it is reasonable to assume that the ‘hit-chance’ of non-directed objects dimishes with the square power of distance (comparable with the intensity of diffuse light).
    As a consequence, a terrestrial planet around Alph Cen A or B, which is on the order of 100,000 times as distant from our inner solar system as the Earth is from Mars, has a chance of being hit by a Mars meteorite, which is on the order of 10^10 (10 billion) times as small as the Earth has.
    Considering how rare Martian meteorites are even here, the chances of any ejecta, in which life is still surviving after the long journey, ever reaching a suitable destination might be negligible.
    Space is simply very, very empty. This is, for example, also confirmed by the fact that so-called secondary binary stars, which were not formed together originally but were captured by eachother’s gravity, are so extremely rare: even giant objects like stars seldom have close encounters in the vastness of space.

  • Ronald August 22, 2010, 6:46

    Further to Enzo:
    I would think that Gaia will be able at least to indirectly detect terrestrial planets around nearby stars by means of radial velocity and astrometry.

    For direct imaging and spectroscopic analysis of terrestrial planets, though, we will probably have to wait for the European Darwin mission, but that one seems to have been postponed (indefinitely ?) as well, like the TPF.
    The question is whether extremely large ground-based telescopes (ELT) with adaptive optics will ever be able to do a similar job, given the infrared absorbing characteristics of our atmosphere.

  • andy August 22, 2010, 15:12

    One thing to note regarding travel of material between solar systems is that radar studies of Earth-impacting meteoroids indicate that there are some that appear to be on hyperbolic orbits originating from the direction of Beta Pictoris, which is known for having significant amounts of orbiting dust. For example, see Baggaley (2000) and Krivov et al. (2004).

  • Zen Blade August 22, 2010, 19:51


    I (as some know) am not a fan of panspermia. I question whether it is even hypothesis-ready. I do not intend to be mean or overly dismissive, but I would almost be willing to compare panspermia to the “singularity” (and its always-vocal supporters) in that these ideas receive lots of hype, but there is little beyond conjecture to support it, and no scientific undertakings that I am aware of.

    But regarding organisms traveling on object XX, I disagree that you would have homogeneity. Yes, on a very small object the size of a baseball you might, but I have a very hard time seeing any organism surviving on an object that size during 1. ejection 2. traveling in space, and 3. entry onto another planetary body.

    On a larger object, I could see local ecosystems developing, or even specialization of organisms working symbiotically, depending on the conditions. Some microbes with smaller genomes may be ideally suited to living closer to the edge of their “home”, at locations that other microbes with slightly larger genomes would not be capable of thriving. Or, perhaps specialization would occur due to the constant exposure to radiation that would necessitate either many copies of a genome (while also forcing organisms into shedding unneeded genes). In this case, some populations might lose gene sets A and B, while keeping C and D. Other populations might keep A and B, losing C and D [Where the final products of A, B, C, and D are required for both populations to live].

    Therefore, a diverse gene pool can still exist spread out amongst a diverse population. However, if any of the organisms alters its environment (takes minerals or nutrients from their “home”), they could easily end up destroying the entire home… I don’t know how quickly certain rock/soil formations can be metabolized/altered by microbes… but I doubt the time is infinite.

    best wishes,
    -Zen Blade

  • Andrew August 23, 2010, 0:19

    Life getting off another planet or Earth for that matter might not need to be blasted off by an impact.
    I read somewhere that smallish critters and seeds have been found very high in our atmosphere.
    Could things like dandelion seeds and baby spiders getting blown really high into the atmosphere could be swept beyond Earth’s orbit?
    OK, it’s a long shot, bit worth considering.

  • Zen Blade August 23, 2010, 12:20

    Interesting article on BBC about microbes in space. They don’t provide enough information about the conditions of the experiment, but if it is published somewhere, I imagine the authors will be much more thorough in describing how the rock was exposed:


  • NS August 23, 2010, 15:02

    Zen Blade’s post above reminded me of a link from another forum. A NASA scientist believes he’s detected fossilized cyanobacteria in meteorites. As you might imagine it’s somewhat controversial though:


  • Ronald August 24, 2010, 7:17

    News just in: HARPS discovers 7 planets around star HD10180 (a G1V star at about 130 ly), a record number so far and also a record density: 5 of these planets orbit from 0.02 to 0.49 AU. Another one at 1.42 AU and one at 3.4 AU. All but two are Neptune/Uranus class. The inner one is only slightly bigger than Earth (another record?), the outer one is Saturn class.

    Hey, the one at 1.42 AU (HD10180 g, about 20 Me) is probably within the habitable zone (defined on basis of liquid water) of this star!

  • Eniac August 24, 2010, 9:14

    In 25 years, we will have not just a philosophical view of life in the universe but a practical knowledge based on data that can tell us whether we’re likely to be alone or simply one among many galactic species.

    These are exciting times. Depressingly, though, if these “near term reads” all come up negative (as they would in the “Rare Life” scenario I consider likely), our philosophical view of life in the universe will not change all that much, and, I think most would agree, for the worse.

    Just as the astonishing past century of astronomy has reduced the imagined realm of life from canal-irrigated civilization on Mars to possible microbes or microbial fossils there and elsewhere, the next century might have imaginings of life retreat further from a galaxy teeming with civilizations to one at most sparsely dotted with planets possibly bearing life in some form. Too sparsely for one to be within reach of any realistic interstellar mission.

    I worry what this steep and steady reduction in realistic extraterrestrial life scenarios is going to do to the motivation for interstellar missions, or to science fiction for that matter…

    On the plus side, the Rare Life scenario still leaves us with billions of Earth-like planets to explore and take for our own.

  • Greg August 24, 2010, 10:29

    I’m not sure that’s true. Over half the biomass of this planet is composed of unicellular organisms, which existed for billions of years prior to anything more complex. And while intelligence has certainly been beneficial to human survival, it also threatens it, as we are the only species on the planet with the capability to wipe out most complex forms of life on earth.


    I totally agree, until we have intelligence that has survived as long as the dinosaurs, approx. 120 Million years, then we can say ‘Intelligence’ is a successful survival trait.

  • Stan August 24, 2010, 12:36

    I’ve just discovered that the idea of panspermia is a loaded, political one. Creationists are using it in their battle against evolution, with panspermia pointing to only one origin of life in the universe, spreading everywhere else from there. It’s sad to see these agendas everywhere. As in the global warming debate. And all the manipulated pharmacological studies. Truth for its own sake is getting harder to find, and to recognize.

  • Alastair McKinstry August 24, 2010, 13:24

    The value of intelligence for a species is that it enables that species to adapt to different niches. Mankind has spread from the equator to the poles, with visits to the Moon and the bottom of the ocean.

    While individual baterial and unicellular species live there, no other species (beyond our parasites!) has done so. We get to survive predation and disease by producing antibiotics. Compare man to less intelligent mammals and you see the evolutionary advantage of intelligence.

    Arguably (though not yet provably) intelligence gives us the evolutionary advantage of getting off this planet / fixing an inbound bolide.

  • Eniac August 24, 2010, 18:06

    I totally agree, until we have intelligence that has survived as long as the dinosaurs, approx. 120 Million years, then we can say ‘Intelligence’ is a successful survival trait.

    Complete domination over all other lifeforms certainly qualifies as a success already, I would think. The best way to top that would be to become the first species to extend its habitat beyond Earth.

  • Zen Blade August 25, 2010, 8:56

    While the end product of intelligence may be advantageous (debatable), the growth stages that lead to intelligence/society are not necessarily advantageous.

    There were a lot of other (presumably) intelligent species related to man, or at least mammalian that did grow into world-spanning species. The exact role of luck, the nature of luck or fortuitous timing, and any number of other factors (which we may or may not currently be aware of) may have led to man’s ascendancy as an intelligent species.

    There are a countless number of adaptation or traits specific to each species. Some are happenstance, coincidentally traits that cause no harm but are not vital to a species survival. Others are absolutely required, but only because of the local environment. Other traits are absolutely required for that organism, regardless of the local environment.

    Elephants, for example, are highly intelligent creatures, they form societies led by females. Is there intelligence the trait that makes (made) them so successful… Was it their size? Was it something else or a combination of factors?

    We can ask similar questions about a number of various species. I don’t think the answer is clear cut. If we argue that adaptability is the single most important trait to survival, then yes, the ability to invent (essentially adapt) is critical to a species survival… but a species does not simply develop this trait overnight.

  • Eniac August 25, 2010, 9:37

    There were a lot of other (presumably) intelligent species related to man, or at least mammalian that did grow into world-spanning species.

    That is news to me. Any basis for this assertion?

    Surely there were a few hominid species with intelligence similar (but inferior) to ours. However, they did not grow to span the world, much less dominate it. Before they had a chance, they got dominated and extinguished by us, their intellectually superior sibling species.

  • Zen Blade August 25, 2010, 20:19


    Why do you say they were “inferior” intellectually???

    You are coupling “domination” or “out-competing” with intelligence in a way that is not necessarily true.
    A fortuitous invention does not equate to “intellectually superior”, neither do slight physical differences (limb length, torso, muscularity, etc…). If you are referring to brain or cranium size… then you might have a point, but even that does not necessarily relate (directly) to intelligence.

  • Eniac August 26, 2010, 11:26


    I said “inferior intellectually” because I think that is the most likely explanation why they, and not us, became extinct. Of course you can argue with that, but I do not think there is any evidence to the contrary.

    There is a lot of evidence in favor, such as the brain size you mention, strong genetic evidence for high selection pressure on central nervous system genes, or simply the large difference in cognitive ability between us and the next living contenders (dolphins, apes, elephants, octopi, what have you). In spite of all the romantic “they are just as intelligent in their own way” notions, none of them would have half a chance in a battle of wits against a human. It is us who make them jump through hoops for show, and not the other way around.

  • Zen Blade August 26, 2010, 16:30


    In case you have not read about Neanderthals and their life/extinction, I have provided this link:

    Here is a case where two groups of Man competed and one lost. There are clear/obvious differences between the two, although brain size does not appear to be one. The idea that they merged into man is NOT correct. Yes, there are signs of interbreeding, but that should really be seen as a minor/rare event. Rare events that produce an offspring with a particular trait of greater advantage can result in the preservation/amplification of that trait throughout entire populations (and fairly quickly). So, there is no need to invoke massive neanderthal/Cro-Magnon mixed populations. However, I acknowledge that some people to invoke such an event… but the evidence for that is not very good.

    Also, if we want to talk about one group of many replacing another group. There are plenty examples of modern man’s migration throughout the world and how later waves of settlers replaced earlier waves not because of anatomical differences, but because of a particular technology that they had stumbled upon (how they made spears or arrows or some similar weapon or housing or tool or etc…).

    -Zen Blade

  • Eniac August 26, 2010, 18:24

    I agree that there are many examples where one group replaced another for reasons other than superior intelligence. However, I believe you will not find many cases among hominids where one group replaced another of significantly higher cognitive ability.

    I believe there was a point in primate evolution where the ability to think crossed a threshold that made it an overriding selective force, elevating it over all other characteristics as a predictor of survival. It may not have had much to do with technology, though. In my opinion, social intelligence (the ability manipulate and outmaneuver others) and language (the ability to collect and transmit information) were initially at least as important as technology (the ability to manipulate the natural environment). Indeed, technology may have been more of a byproduct than a driving force of the evolution of intelligence, albeit a very useful one.

    Technology plays the main role in a much more recent development: The newly evolved capability to collect and transmit information enables the development of technology that in turn improves the handling of information. Writing, printing, telecommunications, and finally the computer. A virtuous circle that freed human advancement from the shackles of the much slower process of biological evolution.

  • Zen Blade August 27, 2010, 12:37


    “I agree that there are many examples where one group replaced another for reasons other than superior intelligence. However, I believe you will not find many cases among hominids where one group replaced another of significantly higher cognitive ability.”

    We just don’t know… I mean, we can’t travel back and time and determine how intelligence affected the struggle for survival/dominance. We can speculate, but without conclusive evidence that can be examined and at least modeled in a modern setting… it is rather difficult.

    For example, we can say culture X with tools 1-4 was replaced by culture Y with tools 3-9. We can then examine those tools, see how much better/worse each one is, and probably come to a reasonable conclusion that having more (and better) tools allowed culture Y to quickly replace/absorb culture X. This assessment assumes that many other factors are relatively not-different.

    The problem is that we can’t just say “their brain was larger/smaller” and therefore they lived/died. It really isn’t that simple. It’s possible that this difference could be the most significant, but there are other factors as well. Yes, I agree that the social interactions/clans/groups of early man were important, and it is easy to see that significance based upon modern man and the strength of a group/family over less organized groups. However, someone could argue that this is a projection that is not necessarily true.