Thread: evolution of life on other planet

http://www.youtube.com/watch?v=Oa79Y...eature=related

i saw this short c. sagans documentary about how evolution on this planet made us look and act like this depending on most common atoms (material) present on Earth - water, carbon, iron...

so how would mars people (or animals and plants) look if evolution there went better way few billion years ago?

imagination ON 8)

There is NO WAY to tell this. At all. Not only do we have no 'raw materials', we have no way of knowing the 'blueprints'. So, ask yourself: How do you build a house that has no starting materials and no blueprints? How do you even imagine that?

Nonscience I say, NONSCIENCE! Still, it's fun. I suggest you check out things like cold water isopods, deep water cephalopods, almost any insect or things like Helicoprion and Stethacanthus for some cool ideas.

The gross composition of Mars and Earth are similar. The initial atmospheric and hydrospheric compositions would have been very close. The surface temperature of ancient Mars, with a thick atmosphere rich in carbon dioxide, would have allowed liquid water. The key ingredients (CHON) for carbon based life would have been present in abundance. If life is a natural emergent property found in "warm, little pools" rich in organics, then it would have emerged on Mars.

What we don't know is whether it would have been based on DNA or a DNA like molecule; whether it would make use of the same amino acids to construct proteins; whether its energy cycle would make use of ATP.

If we can't know these things for the elementary single celled organisms that start things off, then it is wild speculation to imagine what would follow when multi-cellular life forms appear two billion years later.

It is also intriguing to consider how the presence or absence of a significant magnetic field would affect life.

Originally Posted by free radical

It is also intriguing to consider how the presence or absence of a significant magnetic field would affect life.

Migratory patters would have to be based on something else. There's also no moon to fly towards when you want to find a mate. And the gravity is much lower, so flying animals could be a fair bit bigger.

I think that is mostly only true for aves, who actually have magnitite in (I think) the Nasal bone of the skull. Mammals I don't think rely on the magnetic field, or at least I haven't heard of them doing this.

There's also no moon to fly towards when you want to find a mate.

Can't you see Deimos and Phobos from the surface of Mars?

Originally Posted by mormoopid

I think that is mostly only true for aves, who actually have magnitite in (I think) the Nasal bone of the skull. Mammals I don't think rely on the magnetic field, or at least I haven't heard of them doing this.

Cows align themselves to it, bizarrely enough. It's not clear why, though I don't think it would be a wild speculation to suggest that might have something to do with migration.

Originally Posted by KALSTER

There's also no moon to fly towards when you want to find a mate.

Can't you see Deimos and Phobos from the surface of Mars?

Yes, but they look tiny.

Originally Posted by mormoopid

I think that is mostly only true for aves, who actually have magnitite in (I think) the Nasal bone of the skull. Mammals I don't think rely on the magnetic field, or at least I haven't heard of them doing this.

There is some indication of rudimentary magneto sensing in mammals and other groups (insects, fish, other). It seems that the phenomenon may be fairly widespread. Ex:

What causes cetaceans to strand?

Scientists don't know. Some think that whales strand intentionally to rest or seek safety of land or to rub their skin. Others believe that disorientation, confusion of sonar signals in shallow water, or effects of parasite infestation of the inner ear may cause strandings. However, the most compelling scientific theory about strandings has to do with whales using the earth's magnetic field to navigate their environment.

http://www.afsc.noaa.gov/NMML/educat...aceastrand.php

I assume you mean mass beachings? There's compelling evidence, as well as observation, that indicates that echolocation gets confused somehow and one individual gets stranded; their calls in the shallows for help compell others to help them, causing mass strandings.

Of 78 species of cetacea, only 10 species regularly mass strand and another 10 species occasionally strand. Interestingly enough, most mass strandings occur in toothed whales species (such as sperm whales, beluga whales and pygmy sperm whales).

Interesting that it's prevalent in Odontocetes, from memory particularily sperm whales. Weirdly enough, these are the deepest diving and most heavily specialized for echolocation (Re: spermaceti and labyrinth organ). If you look at it, places where military and hardcore pinging and sonar isn't allowed, you have less beachings. So It seems that beachings occur where the sonar is fucked up, rather than some passive magnetosensory.

In short, I am not convinced that it has anything significant to do with beachings and therefore am still not convinced the significance or even presence of magnetosensory in most mammals.

The whale link was simply the first hit regarding mammals. With that said, some who study magnetosensing and Earth history are of the arguably informed opinion that the phenomenon is widespread. It is not uncommon amongst microorganisms certainly, and appears to be a navigation tool for said organisms (Southern hemisphere microbes behave opposite northern hemopsphere microorganisms in a magnetic field.). There is no reason a priori to assume that it would go by the wayside as the evolutionary tree sprouts.

Happily, there is some evidence, as well, , that rudimentary magnetosensing may be present among a wide range of animals as well.

For example insects:

Honeybees (Apis mellifera) undergo iron biomineralization, providing the basis for magnetoreception. We showed earlier the presence of superparamagnetic magnetite in iron granules formed in honeybees, and subscribed to the notion that external magnetic fields may cause expansion or contraction of the superparamagnetic particles in an orientation-specific manner, relaying the signal via cytoskeleton (Hsu and Li 1994). In this study, we established a size-density purification procedure, with which quantitative amount of iron granules was obtained from honey bee trophocytes and characterized; the density of iron granules was determined to be 1.25 g/cm3. While we confirmed the presence of superparamagnetic magnetite in the iron granules, we observed changes in the size of the magnetic granules in the trophycytes upon applying additional magnetic field to the cells. A concomitant release of calcium ion was observed by confocal microscope. This size fluctuation triggered the increase of intracellular Ca+2 , which was inhibited by colchicines and latrunculin B, known to be blockers for microtubule and microfilament syntheses, respectively. The associated cytoskeleton may thus relay the magnetosignal, initiating a neural response. A model for the mechanism of magnetoreception in honeybees is proposed, which may be applicable to most, if not all, magnetotactic organisms.

(For an older more general perspective

Magnetite, the only known biogenic material with ferromagnetic properties, has been identified as a biochemical precipitate in three of the five kingdoms of living organisms, with a fossil record that now extends back nearly 2 billion years. In the magnetotactic bacteria, protoctists, and fish, single-domain crystals of magnetite are arranged in membrane-bound linear structures called magnetosomes, which function as biological bar magnets. Magnetosomes in all three of these groups bear an overall structural similarity to each other, which includes alignment of the individual crystallographic [111] directions parallel to the long axis. Although the magnetosomes represent only a small volume fraction in higher organisms, enough of these highly energetic structures are present to provide sensitivity to extremely small fluctuations and gradients in the background geomagnetic field. Previous experiments with elasmobranch fish are reexamined to test the hypothesis that gradients played a role in their successful geomagnetic conditioning, and a variety of four-turn coil designs are considered that could be used to test the various hypotheses proposed for them.

And specifically with regards to fish:

Diverse vertebrate animals can sense the earth’s magnetic field, but little is known about the physiological mechanisms that underlie this sensory ability. Three major hypotheses of magnetic-field detection have been proposed. Electrosensitive marine fish might sense the geomagnetic field through electromagnetic induction, although definitive evidence that such fish actually do so has not yet been obtained. Studies with other vertebrates have provided evidence consistent with two different mechanisms: biogenic magnetite and chemical reactions that are modulated by magnetic fields. Despite recent progress, however, primary magnetoreceptors have not yet been identified unambiguously in any animal.

And even humans as a possibility:

Although the mineral magnetite (Fe3O4) is precipitated biochemically by bacteria, protists, and a variety of animals, it has not been documented previously in human tissue. Using an ultrasensitive superconducting magnetometer in a clean-lab environment, we have detected the presence of ferromagnetic material in a variety of tissues from the human brain. Magnetic particle extracts from solubilized brain tissues examined with high-resolution transmission electron microscopy, electron diffraction, and elemental analyses identify minerals in the magnetite-maghemite family, with many of the crystal morphologies and structures resembling strongly those precipitated by magnetotactic bacteria and fish. These magnetic and high-resolution transmission electron microscopy measurements imply the presence of a minimum of 5 million single-domain crystals per gram for most tissues in the brain and greater than 100 million crystals per gram for pia and dura. Magnetic property data indicate the crystals are in clumps of between 50 and 100 particles. Biogenic magnetite in the human brain may account for high-field saturation effects observed in the T1 and T2 values of magnetic resonance imaging and, perhaps, for a variety of biological effects of low-frequency magnetic fields.

An intriguing field to my way of thinking! Even if not as fascinating as bats .

Cheers,
FR

haha I know next to nothing about bats, I just think this particular family looks funny.

I can give you a solid example of a structure that has massive implications in some, if not most, terrestrial vertebrates but has been lost almost entirely in mammals: Pineal gland/eye. Logic doesn't have much to do with evolution- for example, why reduce the pineal eye/gland? It doesn't make much sense really, but here we have a direct example of some rudimentary system becoming virtually useless within mammalia.

Heh, we're talking about mammals, not fish and insects! Cool info though! I'm still not convinced that there is any functionality within mammalia for magneto sensory.

Actually, the pineal gland is where a good portion of the magnetite is found in humans if I am not mistaken....

And I am told that size does not matter. Ahem.

Originally Posted by free radical

Actually, the pineal gland is where a good portion of the magnetite is found in humans if I am not mistaken....

And I am told that size does not matter. Ahem.

Awesome.

I thought that a great deal of the magnetite was stored within the nasal area, especially in birds.

Always a fascinating speculation. When we think about other realms, a lot of the rules are thrown out the window.

I had a discussion once with a would-be science fiction writer who wanted to design an imaginary ecosystem in the gas cloud orbiting a giant planet - a bit like Saturn's rings but with lots of gas as well as moons and particles. This guy thought plants would be a problem since they would not grow without gravity, and I had to point out that marine algae, which are almost free of gravity, with salt water buoyancy, do rather well. A plant evolved within a microgravity environment would thrive there.

If such an environment exists, and could develop life, it would be very strange.

Originally Posted by free radical

An intriguing field to my way of thinking!

Was that a pun?

:wink:

Originally Posted by skeptic

I had a discussion once with a would-be science fiction writer who wanted to design an imaginary ecosystem in the gas cloud orbiting a giant planet

Did this guy go on to become Larry Niven?

http://en.wikipedia.org/wiki/The_Integral_Trees

Bunbury
Sadly no. I would love to boast I was a friend of Larry Niven. I enjoyed the Integral Trees, and I loved Ringworld.