Wednesday, February 7, 2018

Cold and Salty


When you and I think of someplace nice to live, we probably aren’t thinking “really cold and super salty”. And yet, there are organisms that do.
After 18 months of gathering cold salty water from remote lakes located in Antarctica - including during the extreme winter - scientists discovered... microbes! One location was Deep Lake, whose water is so salty, it remains unfrozen down to -20°.
At least one strain of microbes contained plasmids, which are small molecules of DNA which can replicate independently in a host cell and often contain useful genes. A plasmid can also grab a piece of DNA from the host cell and incorporate it in itself. They’re certainly complicated, for being so tiny.
Viruses have a protective protein coat that helps them invade unsuspecting cells. Once inside, the virus forces the cell to replicate virus DNA and package it into protein shells, which are pushed out of the ‘nest’ to find their own host cell and repeat the process. Most viruses damage the host cell.
One particular plasmid - called pR1SE - is so much like a virus, the scientists weren’t sure how to classify it. Before this Antarctica discovery, plasmids were known to move from cell to cell when 2 cells were touching, or they wandered around as a piece of naked DNA. However, pR1SE must have thought it too cold in Antarctica to wander around naked, so it had developed a coating of proteins that could attach to a cell wall. Once attached, the protein coat would produce buds (called vesicles), and those buds broke off, taking bits of plasmid DNA to do the same with other cells of the same species.
Virus? Plasmid? This pR1SE version seemed to be something in between. In fact, having discovered this mechanism, scientists are wondering if possibly viruses are ‘more advanced’ versions of plasmids.
Another microbe found in those hypersaline lakes is a ‘cannibal virus’, or virophage, the 3rd virophage ever discovered. This type of virus only infects cells that are already infected with a ‘regular’ virus. As the regular virus uses the cell’s mechanisms to reproduce copies of itself, the virophage inserts its genome into the virus, thus getting the virus to reproduce virophage DNA. The number of copies of the regular virus is greatly reduced, so damage is reduced.
There’s plenty of tiny life in them there super-cold, super-frigid lakes, from things that hardly seem like life (regular plasmids), to something slightly more advanced (pR1SE), through another advancement (viruses) and right to something (virophage) that can try to limit the damage done by the prior version (viruses). Who could have guessed that life in Antarctica would be so complicated?
So, let’s take a lesson from this. Life is complicated. If you are creating a new planet or even just a new continent, try to make the life cycle complicated. I have problems with a planet of sand that produces butterflies and giant worms, and that’s all. If the giant worms only have butterflies to eat, how do they get so big? And what do the butterflies eat?

https://phys.org/news/2017-08-antarctic-salt-loving-microbes-insights-evolution.html
http://www.sciencealert.com/cannibal-viruses-in-antarctica
https://www.newscientist.com/article/2144518-antarctic-mystery-microbe-could-tell-us-where-viruses-came-from/

Thursday, January 25, 2018

Ancient Massacre

Why do humans go to war? It has long been believed that warfare began once early humans abandoned the carefree lifestyle of hunting and gathering in favor of building a home, farming, and establishing villages. People in the next village or the next valley, it was theorized, grew envious of their neighbor’s ‘luxury’, and decided to take it from them.
A single archaeological dig in Kenya may up-end that theory.
The dig site is Nataruk, which is currently dry scrub brush territory some distance from the southwest shore of Lake Turkana in northern Kenya. Human skeletons found at the Nataruk site have been dated to about 10,000 years ago, when Lake Turkana was much larger and the area of the site would have been fertile, perhaps even a marshland. Lots of animals would have used this area to drink, so hunting and gathering would have provided plenty.
What was found at Nataruk are the remains of 27 people, which included 12 skeletons that were relatively complete. When alive, they ranged in age from Old (back then, that meant over 45) to the very young, including one who either had not yet been born, or was an infant being held by one of the women. The archeological team who discovered them believe they died violently or were left to die, and were left unburied. They point to blunt-force trauma to some of the skulls, arrowheads and spear points found embedded in other skeletons, various other broken bones, and indications that some had their hands tied together. Other archeologists debate that these skeletal injuries might have happened after the people were dead.
These 27 people - who all appear to have died at the same time - included 8 men, 8 women and 6 children, with 5 others whose age and gender could not be determined.
Part of the reason why warfare has been assumed to have started after people settled into villages was because - before this - evidence of violence between nomadic groups has been sparse and hard to identify. Researchers mention the Jebel Sahaba graveyard (located in modern Sudan), which is dated to 13,000 years ago and contains the remains of some people obviously killed in violent skirmishes. That this is a cemetery indicates a settled community.
But, my mind says, the entire global population did not start farming and settling into villages at the same time. If food from plants, hunting and fishing were enough to sustain your tribe, and all you had to do was move a few miles every so often, why bother settling down? (Especially if you’ve never heard of such a thing.) Or maybe Nataruk was somewhat more of a settlement than a temporary camp, because the hunting, fishing and gathering was so good.
Whichever way it was, there might have been several ‘nomadic’ groups in the general area. Perhaps some were greedier than others. Or perhaps good eating led to more mouths to feed, and then the climate ‘shifted’ (the wetter late Pleistocene era slid into the drier early Holocene). It wouldn’t take much for the hunting, fishing and gathering to become less bountiful.
I’m not sure I believe that warfare came along only when people settled down, grew crops and started communities. They have found plenty of evidence of violence between nomadic individuals, so I’m not sure why they think warfare (between groups instead of individuals) wouldn’t have happened. They say the earliest group skirmishes happened because one group wanted something the other group had. Why would it be any different if neither group was settled? If a group of nomads were moving, desperately looking for food, and they stumbled across another group’s campfire while they were roasting a few nuts and cutting up a couple rabbits, why would the first group NOT want what the 2nd group had?
It’s something to remember if you are writing about other times and other cultures. We probably have to start by looking humans and their reactions to various circumstances, but I can’t imagine if 2 groups of nomads ran into each other, and neither had enough food to feel their own group, that they’d be very friendly with each other. If you want your alien species to always be friendly, no matter what the circumstances, you’d better figure out how that worked during their prehistory days. Why would sharing resources that really wouldn’t have been enough for 1 group be of benefit to them?

https://www.npr.org/sections/thetwo-way/2016/01/21/463835225/discovery-of-ancient-massacre-suggests-war-predated-settlements
https://www.smithsonianmag.com/science-nature/ancient-brutal-massacre-may-be-earliest-evidence-war-180957884/
http://www.bbc.com/news/world-africa-35370374

https://en.wikipedia.org/wiki/Nataruk