Why MEN?

Why do we have two sexes. Or more specific: Why do we have men? 

Why waste all that effort and energy in producing and caring for offspring that doesn't carry offspring themselves? Kinda pointless, right?

The maintenance of sexual reproduction in a highly competitive world has long been one of the major mysteries of biology given that asexual reproduction can reproduce much more quickly as 50% of offspring in sexual reproduction are males, unable to produce offspring themselves.

"Almost all multicellular species on earth reproduce using sex, but its existence isn't easy to explain because sex carries big burdens, the most obvious of which is that only half of your offspring—daughters—will actually produce offspring. Why should any species waste all that effort on sons?” lead researcher Professor Matt Gage, from University of East Anglia's School of Biological Sciences, said in a statement. 

Researchers from the University of East Anglia (UAE) believe they may have found an answer, suggesting that the evolutionary force known as ‘sexual selection’ plays a key role in improving population health and protecting us against extinction.

"To be good at out-competing rivals and attracting partners in the struggle to reproduce, an individual has to be good at most things, so sexual selection provides an important and effective filter to maintain and improve population genetic health,” said Gage. 

So - 2 sexes is a major asset, when it comes to a species survival in a competitive enviroment. But would it be so universal that we would expect to find it on other worlds as well? 

HALF A BILLION years old ancestors of arthropods found

I just love evolution - if that's possible at all to love a definition. 
But evolution is amazing! Think of all the endless possibilities of life there already has been, the ones that's here now and the ones that will come in the distant future. It really makes my head spin... 

Io9.com just featured this amazing article about these HALF A BILLION years old ancestors of spiders, shrimp and other arthropods. Or possible ancestors at least, since a lot of stuff happens during 500 mio. years. 

Anyone for squidditch? 

Anomalocarids - as they're called - are one of the oldest families of animals on Earth, and they truly looked like something thought up by the combined spawn of H.P.Lovecraft and H.R.Giger. 

From the io9 article:

The connection between anomalocarids and today's animals has long been a source of debate, and some paleontologists believed that there was no way to classify them properly. But thanks to Cong and his team, we have some strong evidence that arthropods — a group containing spiders, crabs, scorpions, and centipedes — are the distant descendants of these anomalocarids.A team of paleontologists led by Peiyun Cong found three gorgeously-preserved anomalocarid fossils in Yunnan Province, and described them today in Nature.

 The main overlap between the two groups, separated by 500 million years of evolution, is their brain structure. Arthropods have segmented, compartmentalized heads like anomalocarids. Plus, their brains connect to those "front appendages" which are called mouth flaps or antennae in today's arthropods. So both groups of creatures shared a very specific physical characteristic, which was a connection between those appendages and the brain.

-Illustration by Nicholas Strausfeld

And above, you can see a side-by-side comparison of one of the fossils (gray) witha a modern arthropod called an onychophoran or velvet worm (green). Long nerves from the frontal appendages extend to paired ganglia lying in front of the optic nerve and connect to the main brain mass in front of the mouth. Anomalocaridids had a pair of clawlike grasping appendages instead of feelers.
New fossil discovery of Anomalocarids actually contains traces of their brain structure — and amazingly, their half-billion-year-old brains look a lot like an arthropod's. Though some anomalocarids may have been as big as 7 feet long, these newly-discovered specimens are closer to the size of today's large insects.

Free Willyanomalocarid!!!!

If you found this interesting, you just might like my post on the origins of life on Earth too.

So just think about all the marvelous alien life there might be out there, beyond the deep, dark and dead vacuum of space, when you see what's been going on this tiny rock. 



Read the article at i09 here.
Read the full paper at Nature.

Some Ground Rules for Alien life

How Stuff Works has a very interesting article about the rules for alien life, written by Craig C. Freudenrich, Ph.D (B.A. in biology from West Virginia University) and Ph.D. in physiology from University of Pittsburgh School of Medicine before completing eight years of postdoctoral research at Duke University Medical Center).

Some Ground Rules for Alien life 

Using what we have learned from life on Earth, what can we say about alien life? While it would probably be vastly different from life on Earth, alien life would probably adhere to certain universal guidelines, as the widely varying life on Earth does. These guidelines or ground rules include the following:Alien life would be governed by laws of physics and chemistry.
Alien life would be based on some type of chemistry (eliminating the sci-fi concept of pure-energy beings).

• Solvent - On Earth, the solvent for all of our biochemicals is liquid water. Other chemicals could be solvents as well, such as ammonia, methane, hydrogen sulfide or hydrogen fluoride.

• Temperature - Alien life may require temperatures at which its solvent can remain liquid.

• Pressure - Alien life may require environmental pressures (and temperatures) that allow solvents to exist in three states of matter (solid, liquid, gas).

• Energy source - Living things require energy to remain organized. This energy may come from a star or from chemical or geothermal energy (as in hydrothermal vents and hot springs). On any alien world, there would have to be some source of energy to sustain life.

• Complex molecules - Living things on Earth are organized and made of complex, carbon-based molecules that carry out biochemical functions. Carbon is a versatile atom that can form bonds with up to four other atoms, in many shapes, to make molecules. Although not as versatile as carbon, silicon can also form up to four bonds with other atoms and has been proposed as a basis for molecules of alien life (silicon-carbon hybrid molecules have also been proposed). It is likely that alien life forms would have some type of complex molecule to carry out similar functions.

• Informational molecule - In Earth organisms, deoxyribonucleid acid (DNA) is a complex molecule that carries genetic information and directs the formation of other molecules in order for life to reproduce and function. Because a characteristic of life is that it reproduces, it seems likely that alien life forms would also have some type of informational molecule.

Alien beings that are larger than microbes would have some equivalent of cells. As an organism gets larger, its internal volume (cubic function) grows faster than its surface area (square function). This places a limit on the organism's size, because substances from the outside of the organism must pass into and throughout the organism by diffusion, which depends upon large surface areas, short distances and differences in concentrations. As an organism grows larger, the distance to its center increases and diffusion gets slower. To maintain workable diffusion distances, an organism must have many small cells instead of one large cell. So, an alien would be multi-celled if it is larger than a microbe. 

Alien life would evolve and adapt to its surroundings by the theory of evolution as previously explained.
The physiological make-up of a multi-celled alien would be most suited to its environment. Organ systems would be adapted to environmental conditions such as temperature, moisture and gravity. 

• The alien would have some way of bringing solids, liquids and gases inside its body, distributing them to every cell and removing waste products (equivalents of heart, blood vessels and kidneys, for instance).

• The alien would be able to take in energy from its surroundings, extract the energy and eliminate wastes.

• The alien would have senses (such as sight, sound, touch) to obtain information from the environment and respond to stimuli (while we use vision as our primary sense, this may not be true of aliens). They would also have some type of brain or nervous system to process information.

• The alien would have some means of reproduction, either sexual or asexual.

Alien organisms would probably have similar ecological structures to life on Earth.

• Population sizes would be limited based on the predominance of food, predators, disease and other environmental factors.

• Alien life forms would exist in food chains and food webs in their native environment, like life on Earth. Producers will make food, consumers will eat producers and/or other consumers and decomposers will recycle atoms and molecules from dead organisms back into the environment.

• Alien life forms will be integrated with their habitats and ecosystems, like life on Earth.

As you can see, life of any kind is intimately tied to its environment, so the characteristics of the planet would be extremely important in determining the characteristics of the life form. 

A very nice article with a very straight forward approach, focusing on the nature and evolution of an alien world and whatever life might be found there. Especially that life on that planet ought to fit into it's native ecosystems, even if it has removed itself from it's natural place in the food chain (E.g. via civilisation), it would still have kept the same traits, physically as well as psychologic.
Talking about food chains and ecosystems: That might cause problems if we ever decide to colonize alien planets already containing native lifeforms - how would we fit in? Would we be able to digest anything at all from that planet? And how would our dead bodies on the other hand decompose on the alien world, without risking a genocide?

Art by Alex Ries

http://abiogenisis.deviantart.com/

Origin of Life?

One of the questions that's been annoying me for years is this: What is the point with life?
Not "what's the point" in any general or philosophical way, but literally: What IS the point?
And don't bother bringing God into this. It's a whole other discussion, and I'd be happy to take that up later, but for now I'm on another mission.

Because what is the point with life?

Everything else in the universe seems to fall into some patterns or laws, which gives some kind of purpose. Gasses come together and form giant clouds that becomes structures that becomes stars and planets - all bound by laws of physics. The planets are kept orbiting stars, stars orbiting the galaxy etc. It makes kind of sense! It's there because it cannot not be there! It's a kind of universal evolution. I'm probably speaking against better knowledge, but then I'd love to be educated. Life doesn't seem to follow laws as such. It's just a byproduct - something that accidentally popped up on this tiny cockwheel in the universal clockwork.

So how did life come to be? Is it a physical reaction of chemicals and lightning, or a freak accident?

A young MIT scientist, Jeremy England (By the way - isn't that just the coolest name for a science guy ever?) has come up without very interesting thesis: Life evolved out of a necessity on an atomic scale:

"From the standpoint of physics, there is one essential difference between living things and inanimate clumps of carbon atoms: The former tend to be much better at capturing energy from their environment and dissipating that energy as heat. 

Jeremy England, a 31-year-old assistant professor at the Massachusetts Institute of Technology, has derived a mathematical formula that he believes explains this capacity. The formula, based on established physics, indicates that when a group of atoms is driven by an external source of energy (like the sun or chemical fuel) and surrounded by 

a heat bath (like the ocean or atmosphere), it will often gradually restructure itself in order to dissipate increasingly more energy. 

This could mean that under certain conditions, matter inexorably acquires the key physical attribute associated with life."   

He states that the origin and evolution of life are processes driven by the fundamental laws of nature — namely the Second Law of Thermodynamics. He's come up with a formula showing how a group of atoms, when driven by an external source of energy (like the sun) and when surrounded by a heat bath (like the ocean or atmosphere), can sometimes restructure itself as a way to dissipate increasing rates of energy.

So, according to the Jeremy England, the origin and subsequent evolution of life follow from the fundamental laws of nature and “should be as unsurprising as rocks rolling downhill.”

“You start with a random clump of atoms, and if you shine light on it for long enough, it should not be so surprising that you get a plant,” England continous.

The thesis has gained a lot of response from the scientific community - responses reaching from  "interesting" to "absurd" and "pure speculation."

I'd go with "interesting" here, because it kind of makes sense to me. 

Of course, this planet could for all we know be the only one with any kind of life on it. We might just have to face the fact, that we are alone in this universe. But it would be odd, wouldn't it?

I guess that if the theory of Jeremy England is true, chances on finding traces of life on Mars just got beefed up...

Wanna know more? //www.simonsfoundation.org/quanta/20140122-a-new-physics-theory-of-life/