Sulfur played a vital role in the history of life on earth a new study says, and the fact that sulfur was abundant in the early earth, meaning plenty of material for microbes to metabolize to serve as fuel for photosynthesis, means that the abundance of sulfur in the early earth played a vital role in the oxygenation of the earth’s atmosphere.
However, because sulfur quickly degrades in an oxidized environment, the sulfur chemistry of early life on earth was “quickly lost to time,” as the article says.
Because sulfur is quickly oxidized in an oxygen-rich environment, and then removed from the atmosphere by precipitation and run-off into the ocean, the sulfur chemistry of early Archean life was phased out and lost to time. However, by understanding the mass independent fractionation process, it should be possible to learn more about the atmosphere of the pre-oxygenated Earth and the conditions in which the first life on Earth lived.
The process behind the mass independent fractionation of sulfur remains uncertain, but the two most popular hypotheses are either photolysis (the breaking apart of molecules) by ultraviolet light from the Sun, or reactions between elemental sulfur. “However, the actual phenomenon, reaction or mechanism is still to be identified,” says Dmitri Babikov, a Professor of Physical Chemistry and Molecular Physics at Marquette University in Milwaukee, Wisconsin.
The article says that sulfur isotopes could serve as potential indicators of environments similar to that of the early earth’s, but that today’s technology is too limited to be of any help in identifying such indicators in potential exoplanets. Let’s hope the Jim Webb telescope is launched soon, for much is yet to be learned about the universe at large.
Kleinman has challenged me to “do the math of the chimp-human lineage,”
since six million years is roughly equivalent to six hundred thousand
generations, and herein I’ll show how it’s far easier to calculate than
he thought. On average, at conception, you start out with 150 new
mutations right off the bat, something Kleinman should be aware of, and
since for the purposes of this calculation six million years = six
hundred thousand generations, we will calculate 150 times 600000 and see
what we get.
150 x 600000 = 90000000
So, knowing that at conception you have 150 mutations right off the bat,
and that there has been roughly six hundred thousand generations since
the LCA of both humans and chimps, we can safely assume a minimum of
ninety million mutations having occurred since then cumulatively in each
generation from the past to the present.
Kleinman’s one pony trick, the so-called “replication issue,” is easily
solved when one realizes we’re dealing with relatively small populations
isolated from each other by both time and space, and hence mutations
could spread far more easily in such small populations than they can in
a population as large as that of modern humans, which for most of
history was also relatively small, having ballooned only in the last 10k
years since the invention of farming.
The Good DrDr may contest this by asking how many of these mutations
were “beneficial mutations,” and as we shall see only the environment
determines whether a mutation is beneficial, neutral, or negative,
something DocDoc contests but is true nonetheless.
The above is a useful overview of what we know about the first invention of fire by early humans and its effects on mankind’s evolution. The earliest definitive use for fire use is around a million and a half years old, but phylogenetic analysis puts the invention of fire further back to around two million years ago, this is corroborated by the anatomical characteristics of species like Homo erectus, with reduced jaws and teeth that in some cases were the size of the teeth of modern people, as well as more reduced musculature compared to the non-human great apes and a far bigger brain in relation to body size than australopithecines, our ancestors, and great apes, with cranial capacity reaching up to 1100 cm.
The earliest evidence for habitual fire use dates to around 500,000 years ago, and we have indirect evidence that we were making glue from around this time too, see the article for more details on that. There’s some evidence both Neanderthals and early modern humans practiced fire stick farming from at least 120,000 years ago, and there’s evidence of leather working from around this time, for those who don’t know leather requires fire to make, and there’s also evidence for hand drills from around 400,000 years ago as well, instead of simply using the friction from rubbing two sticks together in an hearth on top of some kindling to ignite a fire, which is presumably the first method we devised for actually making fire.
We likely had the ability to control fire before we invented methods to ignite it, this would require knowledge of slow-burning materials to maintain fires for long periods of time, animal dung does the trick.
Scientists recently utilized genetic evidence to reconstruct what Denisovans looked like, and the results are astonishing. For one they would’ve had wider skulls than both neanderthals and modern humans, as well as having a longer dental arch. It brings these ancient humans to life in a way that mere bones never could, and it’s humbling to think that these people were among our ancestors, because they were.
Reconstruction available here
I’ve had to deal with this particular piece of creationist claptrap so many times I’ve decided to write this refutation once and for all and be done with it. Abiogenesis is not evolution, it never was, it never will be. Evolution only deals with how living beings change over time, note that in order to qualify as “living,” one has to be alive. The theory of evolution does not concern itself with abiogenesis, that’s a completely different field of study not even belonging to biology, abiogenesis is properly chemistry, not biology.
If one happens to feel the need to make believe that a god created life on earth but allowed life to evolve after that, go ahead, evolution does not conflict with such a belief because it only deals with what happens after life has originated, not before it. One final thing, cars are irrelevant and bringing up how cars need to be intelligently designed and how they don’t evolve is a strawman, cars aren’t living beings that reproduce, metabolize, and possess a genetic code. Piss off.
Abstract: Complex projectiles—propulsion via mechanical aid—are considered an important technological innovation, with possible relevance for the successful Out-of-Africa dispersal of our species. Conclusive evidence for the beginning of this technology, however, is lacking from the early Late Pleistocene (ca. 130 to 70 thousand years ago; ka). Given the extremely limited applicability of relatively robust methods for validating stone-tipped projectile use, such as through fracture propagation velocity, converging lines of circumstantial evidence remain the best way to examine early complex projectiles. We assess here suggestions for an early Late Pleistocene origin of complex projectiles in Africa. Results from both previous and present independent approaches suggest a trajectory in which complex projectiles were likely adopted during the early Late Pleistocene in eastern Africa. At Aduma (Middle Awash, Ethiopia), morphometric, hafting, and impact damage patterns in several lithic point assemblages suggest a shift from simple spear technologies (thrusting and/or hand-cast) to complex projectiles. Broadly dated to 80–100 ka, lithic points from later phases of the Aduma succession represent a particularly strong candidate for projectile armatures most comparable to ethnographically known spearthrower darts, lending support for previous suggestions and warranting further investigations.
Notes: This is interesting, very interesting, because it pushes back the date of the invention of the atlatl back to the Middle Paleolithic, long before modern humans spread out of Africa, and also long before the earliest evidence for the atlatl in the archaeological record, which AFAIK is from Aurignacian Europe, it’s also telling because Native Americans lacked the atlatl until the advent of the Archaic period, so either the ancestors of the Native Americans lost the atlatl sometime prior to the peopling of the Americas or the atlatl wasn’t as common as previously believed. The Tasmanians also lacked the spearthrower or atlatl, despite ultimately coming from the same population that left Africa as the rest of us did, while the Australians *did* possess the spearthrower, called the *woomera* there, although it was of recent (Holocene) derivation.
Very interesting, and this species demonstrates many similarities to Homo floresiensis, including sharing many basal traits with australopithecines and early members of the genus Homo. One wonders how it got there given even at the time Homo luzoniensis lived Luzon was still separated from the Asian mainland by miles of ocean.
The fact that *two* species of primitive human were found in the region at the same time suggests human evolution in the region was far more complicated than previously thought, but this is in line with the discovery of stone tools in China dating back to over two million years old.