A little speculation of my own (with a little help from my friends)
SULFUR. Stephanie Seneff, waxes eloquent on the virtues of sulfur, and Michael Medler, a physical geography at Western Washington University who works with fire, literally and figuratively. Besides his fire ecology work, he also is the father of there girls (19 and 17 years, and 8 months), who keep him on his toes. Also, he is a brilliant scientsist.
Medler links fire geography with human development, after Wrangham’s excellent work, and I quote:
I believe a far more compelling argument for hominin adaptation to fire is Wrangham’s (2009) argument that, without fire, these small toothed, short intestined creatures would simply have trouble chewing and digesting enough uncooked food to sustain themselves (Carmody and Wrang- ham 2009, Wrangham 2009). (p 16)
Medler argues specifically that our consumption of cooked foods provided more efficient digestion, leading to shorter intestines, smaller mouths, smaller teeth, and ultimately freeing caloric resources to support increased brain sizes.He proposes that, around two million years ago, a group of Australopithecines achieved enough savvy to keep the homefires burining (like protecting burning coals) so that they could start eating cooked foods. That meant easier access to calories and also freed up a lot of time that previously had been spent in chewing. This is speculation, of course, but it is at the core of this type of hypothetical thinking. (pp 16 and 17).
Though Wrangham’s cooked food hypothesis was first proposed in 1999, more evidence supporting many of the key arguments of his cooked food hypothesis (Carmody and Wrangham 2009). P 17
Medler argues that
…eventually, large brained, bipedal, cooked-food eating, tool using, Homo erectus emerged and mastered the quintessential human technology when they learned to make fire itself. This technology allowed them to move out into the rest of the world, taking a new kind of fire with them that would change the ecosystems everywhere they went. P 21
According to Medler, if Wrangham is correct (that a population of Australopithecines achieved control of fire and were consistently eating cooked food by about 1.9 million years ago, leading to the emergence of Homo erectus), and Medler is correct, then we should expect to see extensive lava flows into basins in the Olduvai Gorge region at the time of this transition. Fortunately, expectation rose to the category of a reasoned hypothesis with the publication of a paper by (2009).
What does this all mean? As Medler writes (2011),  such a lava flow would have provided 200000 years of continuing access to fire for small isolated groups of hominins that may well have eventually become Homo erectus, mastered fire, colonized Europe and Asia, and created Chicken McNuggets and crocs. Armed wight this powerful tool, they would have changed ecosystems everywhere they brought their fire. 21-22
So here’s my thought: As they moved closer to these lava flows, they would also have been very close to sulfur emissions.
Um, isn’t sulfur a pollutant? Like, one of the EPA’s criteria pollutants for air contamination? Growing up in LA, in the San Fernando Valley even less, in the 1950s and 1960s (i.e. during a huge car boom in LA), and not living near the ocean (where ozone seems to be more of a problem than sulfur, another story), I suffered from all sorts of respiration ills, although not as much as my friends.
Could it be the protective fats I was eating in my Italian home? Is that why my friends begged to come to my house, not for the conviviality of the meals, but for the fat of it all (organ meats in the sausage, and plenty of ground meat and cheese, eggs in the ricotta, and nuts in my cannoli, etc. – lots of saturated fat and cholesterol, protecting against oxidative damage done by sulfur, which, at the same time was a valued nutrient – indeed – most cells can only use cholesterol sulfate in their membranes).
In graduate work at Cornell, I found the manure and farm smells of the open countryside most inviting. I was so enamored with both, I decided to make the organic agriculture world a research area. Off I went to the sulfurous Allegheny mountains, and Kenya’s famed great African rift, to volcanic Alaska, and now Washington state with sulfurous Baker. We can all trace similar personal bio-geo-chemical life cycles. Little did I know, that my own research would be following sulfur flows.
So, back to the Neanderthals (metaphorically speaking), they would have found fire – but also, in the lava flows, they would have found life-giving sulfur as well.
 -Fire Ecology Volume 7, Issue 1, 2011 doi: 10.4996/fireecology.0701013
Wrangham, R. 2009. Catching fire: how cooking made us human. Basic Books, New York, New
York, USA. Wrangham, R., D. Cheney, R. Seyfarth, and E. Sarmiento. 2009. Shallow-water habitats as
sources of fallback foods for hominins. American Journal of Physical Anthropology 140:
630-642. doi: 10.1002/ajpa.21122 Wrangham, R., J.H. Jones, G. Laden, D. Pilbeam, and N.L. Conklin-Brittain. 1999. The raw and
the stolen: cooking and the ecology of human origins. Current Anthropology 40: 567-594.
 And, of course, that goes with being smart, and, of course, that’s what we humans are, Madagascar notwithstanding.
 You’d think this would be pretty much a no brainer – hauling little burning embers around with them. However, I noted that on one of the Survivor shows last week, entitled “Naked,” it took an ex-marine, on his own, about ten days to figure out how to get (and keep) a fire going.
 Fire Ecology Volume 7, Issue 1, 2011 doi: 10.4996/fireecology.0701013