13 posts • joined Friday 29th June 2012 05:33 GMT
Thanks for those great points.
We can throw in another: Endurance running which is associated either with a scavenging lifestyle or with running down prey until they collapse with heat exhaustion. While Homo habilis had some of the necessary characteristics, a much fuller set are present in H. erectus. (http://www.clas.ufl.edu/users/krigbaum/proseminar/Bramble_Leib_2004_nature.pdf). This is suggestive that in H. erectus meat (or large animal fat and meat) were increasingly important food sources.
It's worth laying out a time line here:
~2mya, Homo habilis: Diet was mainly vegetarian but likely included insects, small animals and possibly a very small amount of meat (c.f. chimpanzees who's diet include 5% meat)
1.8mya->300kya, Homo erectus: Evidence scavenging mammal long bones and cracking them open for marrow. First evidence for controlled fire and cooking at 1mya. Strong evidence for endurance running.
~600-200kya, Homo heidelbergensis: Strong evidence for cooking. First evidence for symbolic thought .
~300-30kya, Homo neanderthalis: Enlarged hyperglossal nerve, anatomically similar hyoid, modern FOXP2 allele, strong evidence for symbolic thought; this is strong evidence for language.
The most recent evidence I've seen for cooking is: http://www.nature.com/news/million-year-old-ash-hints-at-origins-of-cooking-1.10372
In summary: there is some contentious evidence of controlled fire with bone fragments in Wonderwerk Cave in the Northern Cape province in South Africa, dated to about 1mya. There is much stronger evidence of cooking dating to 400kya, which is still some 200k years before the emergence of modern humans.
As for talking (as opposed to simple vocalisations), this is even more contentious. The Wikipedia article (https://en.wikipedia.org/wiki/Origin_of_language) is a good summary, positing the first controlled vocalisations were from Homo heidelbergensis (600-200kya for certain, but perhaps as old as 1-1.3mya).
Compared to heidelbergensis, Neanderthals (300kya) had a much enlarged hypoglossal nerve (for control of the tongue) and throat bone (hyoid) similar to ours indicating language had started by this time.
With regard to meat going off, I'll have to disagree with you. There are numerous species that eat rotting/rotten meat such as lions, hyenas and vultures (yea!) without harm. Indeed humans do too - here's a link to Reddit on the topic: http://www.reddit.com/r/askscience/comments/19ztos/why_is_it_that_animals_can_eat_rotten_meat_and/c8syno1
I actually saw the documentary seen by jetpacksforall - it made my stomach churn just looking at it, but only the ethnographer and crew seemed concerned in any way. I suspect that those children that can't fight of the bacteria don't make it to reproducing age :(
I badly screwed up logic and grammar, so I withdrew my first attempt. I'll try again:
Umm, probably the other way round. First tentative evidence of cooking is from about 1 million years ago - before modern humans and before our ancestor could talk. You get 25-40% more energy out of cooked food, and so this would have been a real boost to our ancestors.
This explanation is evolutionary. Those creatures that prefer, say, fatty food (when fatty food was rare) to tree bark survived periods of famine better. Those preferences are genetic, and so are selected for if they have positive outcomes. Over time slight preferences become strengthened and universal if they are strongly beneficial. This happened in our ancient history for high calorie food, so a good number of species love fatty and/or sugary food. As mentioned above, evidence of fire-making and cooked bones is strong at 200,000 years, and probable for up to 800,000 years before that.
'[Cooking] makes the food fucking delicious' is therefore the evolved response to cooked food giving us more calories.
Interestingly cooked foods (those delicious crusty brown bits) are slightly carcinogenic to animals like rats but not to us (well, *red* and processed meats are, but that's another story). This is almost certainly another adaptation in our species that separates us from the rest of the animal kingdom.
Re: Boffinspeek galore
Just to add:
1) 'Shield', 'terrain' and 'craton' are all pretty much interchangeable (to a five year old geologist)
2) What the geologists are saying is that the water that passed through into the underground ultra-mafic rocks got trapped billions of years ago (evidence: quantity of and isotopic ratios of Xenon to other stuff. Xenon comes from the radioactive decay of Uranium/Thorium in the ultra-mafic rocks). The water reacted with the rocks (evidence: serpentine). The water contains reducing gasses that *could* be a food for bacteria which would oxidise the gasses using the rocks.
3) A biome is a self-contained volume where life does its life-stuff. In this case the waters and any life in it have been sealed off from the outside world for billions of years, and by virtue of being sealed off, it is in a different biome from us (or at least *was* in a different biome until some dirty engineers drilled a non-sterile hole into it)
4) Mars has some terrains (or shields if you will) just like the ones on earth
5) If i) this could happen on earth, and ii) there was life on Mars, then iii) it's possible that a ultra-mafic/serpentine/water biome has kept life (well) alive on Mars until now
Re: Boffinspeek galore
Or even more "like I'm 5"
The earth has large plates that move around - we call the plates with bits of land on top 'continents'. Geologists think of these plates as roofs over the mantle and, being boffins, use ancient Greek to show off their knowledge. Tectonic simply means things of or relating to a building. Indeed, the word 'Architect' originally meant chief builder.
As the continents come together mountains are formed like the Himalayas and the Andes. Sometimes forces from deep inside the earth cause a continent to break up - we can see such a break up happening right now in Africa's great Rift Valley. Some parts of the plates we currently have have (miraculously) remained pretty much untouched for billions of years - these areas contain really old rocks and are so distinctive they have a special name 'cratons'. Central Africa, Australia and Canada have such ancient 'terrains'. They can also more confusingly be called "tectonically quiescent (no mountain building or continental break-ups) geologic terrains".
Ultramafic rocks are very similar to those deep below the crust in the mantle - they are harder and denser than the lighter rocks on or near the earth's surface (like sandstone and granite). They are unlikely to have been from volcanoes spewing lava (since only the un-ultra-mafic chemicals melt to form lava), and so come from deep down inside a volcano.
When you pass water through ultra-mafic rocks the crystals slowly 'rust' and turning green and brown. In the middle ages, the colour and texture made people think of a snake, and so called the rock serpentine.
You had me at Wickramasinghe...
... but the other give-away is "nitrogen depleted". Depleted is an implicit hypothesis that there *was* nitrogen there originally, and the nitrogen disappeared because they the fossils are "ancient".
But we also have (as the article acknowledges) no problem with carbon and nitrogen spontaneously forming amino acids in space which survive.
This reminds me of the great life-on-Mars storm in a teacup: http://en.wikipedia.org/wiki/Allan_Hills_84001
But this future will never come
RAM sizes today mean that I can use in-memory databases for the kind of data problems I was handling in the 90's. I remember my first *million* row database. How quaint it seems today.
Just as system memory sizes have grown over the decades, the size of the problem that they *can* address has also grown, so we are today still surrounded by spinning rust.
Tomorrow will be the same. Just as today's systems are orders of magnitude greater than a decade ago, BigData is an orders of magnitude greater problem which will continue to require spinning rust.
So I'm not so hopeful that it'll all fit in memory...
Ooooh the irony
So, after spending the best part of 15 years screwing competitors and partners with secret APIs, unannounced API changes and even code that detects competitors and issues spurious warnings (remember DR DOS?), Microsoft finds itself at the other end of such 'competitiveness'. Oooh the irony.
Technically, an "inclusion" is ...
a fragment of something *inside* another crystal or rock.
So the panguite crystal was inside another mineral - a refactory mineral - that was formed by melting the primordial (pan)gu. Such melting typically ends in a separation of chemicals (think distillation of primordial beer into the refactored spirit and whatever you call the crud that's left behind). One portion of the melted minerals oozed over and around the panguite and the lot froze solid before the panguite crystal could melt. The new wrapper protected the panguite crystal for 4.5b years until exposed in the laboratory.
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