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Mariana Ruiz Villareal
Calculations of dinosaur biomass suggest that plant-eating sauropods like the ones pictured here in an artist's conception could have contributed enough methane to warm Earth's climate 150 million years ago.
Some scientific findings are just too good to leave alone, even if you don't know if they can ever be confirmed: Such is the case for a study saying that plant-eating dinosaurs could have emitted enough digestive methane to warm Earth's climate 150 million years ago.
"It is known that the time of these dinosaurs was warmer than now," said David Wilkinson, an environmental scientist at Liverpool John Moores University who's the lead author of a paper on the subject appearing in the journal Current Biology. "This is explained usually by an enhanced greenhouse effect, mainly carbon dioxide. If we are correct, then methane from sauropods may have been a contributor to this greenhouse effect."
Methane is a more potent greenhouse gas than carbon dioxide, and modern-day livestock are thought to be responsible for about a quarter of the methane released in the United States. Some say that the belches and flatulence of cattle, pigs and sheep are a significant contributor to the warming effect caused by greenhouse-gas emissions. So why wouldn't it have been the same in the age of giant plant-eating dinosaurs, when global biomass density was at least several times what it is today?
"All vertebrates that feed on leaves, etc., use microbes to help digest these, and usually give off methane," Wilkinson told me in an email. "This includes both mammals and reptiles. ... Although details vary within groups, everything around today does this, so the assumption is [that] larger herbivorous dinosaurs did as well."
He and his colleagues ran the numbers, using what they saw as conservative estimates for the total amount of dinosaur biomass and methane production rates per kilogram of body mass. They came up with a figure of 520 million tons of methane emitted per year, which is more than total modern-day methane emissions from all sources, natural and industrial. The current estimate for total methane emission is around 500 million tons a year, with 50 to 100 milllion tons of that coming from ruminant animals such as cows and goats, Wilkinson said.
"Our work certainly suggests biology and climate were involved in a feedback loop," he said.
Biologists have found that most of the modern-day methane emissions from livestock come from belching rather than flatulence. Was it the same for dinosaurs? "We have no particular view which end of the sauropod the methane came out," Wilkinson told me. "Could be either or both."
Chemical analysis of ancient marine sediments has found that greenhouse-gas levels went through a huge rise 201 million years ago, around the time of a mass extinction that set the stage for the rise of the dinosaurs. Scientists suspect that the atmospheric methane levels at that time were pumped up by a massive release of methane from the seafloor. Such evidence suggests that plant-eating dinosaurs weren't responsible for starting the upswing in Mesozoic methane. But did they help preserve the methane-rich atmosphere and toasty temperatures until they were killed off by an asteroid strike?
Wilkinson noted that his paper was titled "Could Methane Produced by Sauropod Dinosaurs Have Helped Drive Mesozoic Climate Warmth?" — not "Did Methane Produced by Dinosaurs Help Drive Climate Warmth."
"What our simple calculations show is that, yes, it could. It's a real possibility. But we don't show that it did happen," he said. "That would require much more work, and indeed it may be impossible to completely prove this without a time machine."
Extra credit: A dozen years ago, the BBC quoted a Chinese news report that quoted an unnamed French scientist as saying the dinosaurs were wiped out 65 million years ago not by an asteroid, but by their own flatulence. This hypothesis proposed that the methane emissions from the giant beasts became so great that the climate changed, the vegetation withered and the dinosaurs all starved. But that's just too silly to consider. Or is it?
More about methane:
- U.S. claims success in fuel source test
- Herb quells cows' methane-laden belches
- Did methane 'burp' clear way for dinosaurs?
- Methane seeping from ice becomes climate concern
In addition to Wilkinson, authors of the Current Biology paper include the University of London's Euan G. Nisbet and the University of Glasgow's Graeme D. Ruxton.
Alan Boyle is msnbc.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.
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Well if the dinosaurs could do this then certainly our Congress can.
They do...... and in monsterous amounts. In a recent scientific study done in my bathtub I have concluded that the global warming phenomon is, in fact, the direct result of both houses of congress blowing noxious amounts of methane and carbon dioxide into the atmosphere.
I know a few old dinosaurs that contribute to it even today!!!
No respect for our lawmakers. I can understand that!
At the least the Dinosaurs were adding mass, growing and being productive, and contributing to their Dino-Economy, the warmer climate was laying down Algae deposits that today supply fossil carbon energy used by humans today.
The gasses emanating from the halls of Congress, are toxic in ways that animals waste never capable or and are destructive of the best humans can offer intelligence. The Dinosaurs never actively sought the destruction of the Earth, except by making the world a better place to live. The Dinosaurs never saw what hit them, today we have C-Span, and the difference is we can see I coming but just cannot believe it. The Earth's first and only intelligent bent to its own destruction, without trace of regret, and to think that even Congress started out with good intentions.
Seriously, Alan?
If the author of this study - Ruxton - is right (and he's made a lot of assumptions here), sauropods warmed the planet by about 1 °C, according to David Beerling, who models climates at the University of Sheffield (UK). Remember that the climate was much, much warmer during the Mesozoic Era, so an incremental increase of greenhouse gases like methane would have a far smaller impact.
That's hardly enough to kill them off. We've already seen that level of warming from human-caused greenhouse gas emissions, and we're still here. You don't do science any favors when you report on scientific issues with statements like that.
If this is true, imagine how much methane that big, fat, gas-bag Rush Limbaugh farts out each day. When you factor in the FOX NEWS HOUR I think we've got pretty good handle on what's causing global warning.
Save the planet, silence Limbaugh and FOX!
(Sorry Alan, but some targets of opporutnity are too good to pass up)
We haven't been burping them out for half a million years, either.
I bet algore puts out more than all dinosaurs together. and becoming a vegatarian goes against nature. the location of our eyes proves we are a predator species.
We are an omnivorous species. We can eat anything, just about.
This article must have been written on April the 1st.
These scientists need to get off the crack. that sh-t is bad for thinking rationally, and these guys are not thinking rationally. Dam I wish I could legally get that HIGH!!!
And so it was determined that a dinosaur dad was the first to play "quick, pull my finger" with his kids.
The current HUMAN population is gassing up the environment far more than dinosaurs with their farting, than any other way, Coal fired plants and hydrocarbons are overwhelmed by volcanoes, nuclear weapons, and farting greenie weenies.
I'm pretty sure my brothers play a big role in this "global warming"!!!!
Wow, someone wrote this article with a straight face?
Makes you feel all warm and fuzzy about the state of science today.
Well, not a totally straight face. Just couldn't resist it ... though I tried to play it straight rather than playing up the "dinosaur fart" angle. There, I said it.
All laughs aside...I've wondered about this since all the talk about cows and their contribution of methane! One could surmise that the Dino gas had the atmosphere saturated and the asteroid and volcanic activity just pushed things over the edge. I would like the see how much methane the current human population is contributing....may have to legally limit burrito consumption!
Alan Boyle. You have been reading too, too many comments from newsvine, if could be affecting judgment. Gas and fumes etc.
Concerned -
Yes, I do feel all warm and fuzzy - Wait, Hold on - There that's better - I think I just bumped the earth's temperature up at least half a degree with that one and still feel warm (seat) and fuzzy (vision).
So just what are the implications of all of humanity going vegetarian?
Let's face it. . .flatulence sells. But when you think of the sheer amount of biomass this planet must have had at one time (think oil, natural gas and coal deposits), almost all of which emits methane as it decays, whether it's been processed through a dinosaur first, or not. . .it's not a great leap. Besides, those gargantuan piles left behind keep cooking-off methane till they decompose, completely. The off-gassing of the sauropods would have been a minuscule, but measurable factor, overall.
My worry is that this kind of story fuels the 'Scientists are Idiots' crowd. Not a good thing.
About the same as removing automobiles from the planet. Which is why I went vegetarian 5 years ago. It's easy, it's cheap, it's better for you and the planet - and it doesn't require waiting for Congress to come up with something to address this problem. You can do it today.
And it makes a huge difference. When you stop eating meat, you effectively counterbalance the carbon footprint of your car. From Scientific American:
Finally! The mystery of global warming has been solved, Farting Dinosaurs. I knew it all along!
The article actually reminds me of the movie Freaked. Not only did it have an all star cast with Mr. T, Bobcat, and Keanu Reeves, but it had the eternal flame. A freak who constantly had a flaming fart like some of the dinosaurs likely could have easily produced. Bless you Lee Arenberg and your constantly flaming flatulance.
Pointless. OMG dinosaurs farted!
It's not inconceivable that this slightly silly news could revive the discussion over regulating methane emissions from livestock...
What about the methane emissions from more than 7 billion people?
Would Al Gore propose a flatulence tax?
Beano for cattle on the horizon .... ??
Alan Boyle
Hence the previous articles on growing meat in tanks... "Spool me up six feet of London Broil, please!"
I thought that ruminant flatulence prevention was still on the United Nations' agenda. In a related story, Portugese cork futures are soaring and their economy could use a plug.
I recall reading a year or two ago that some simple food additive (oregano?) made cows emit less flatulence.
Of course, a much bigger win would be to dramatically reduce the production of cattle and move human diets closer to plant-based protein.
In a way this article just points out the hopelessness of trying to control the climate. Don't get me wrong I am all for reducing the damage done to our planet by human society. My problem is that we are so busy screaming about the potential of climate change that we forget about the rest of the mess we are making. I have actually heard otherwise rational people speak of nuclear power as being GOOD for the environment. A more balanced approach to the situation might sell a lot more people on the need to reduce emissions instead of the climate related scare tactics. Running around giving beano to cows is not as important as the excessive disposal of unneeded waste products or the endless stupid things we do to add value to products. (For example why in the name of all that is logical do we need to BLEACH toilet paper?) The climate will change and change yet again. We need to broaden our perspective to include soil and water quality instead of fighting this one dead issue that nobody can agree upon.
Jim- Then we would have 7 billion farters. Jee, I don't know...
The former head of the Sierra Club to name just one.
Just when you've heard it all... too funny.
So, NOW we know why the sauropods evolved such long necks. To get away from the smell.....bada boom!
OMG that's why they evolved into birds! Ur a genious!!
Evolution at it's best.
I suppose the Chicxulub meteor would've resulted in a much bigger blast by igniting all the methane floating around at the time.
It was also known as the Flatulencian Period.
This is what happens when you want to drive those big, fuel guzzling models. Neanderthals never should have started driving SUVs (Sauropod Utility Vehicles). They should have stuck with more economical models and maybe Neanderthals and Dinosaurs would still be around.
I'm also surprised there's been no mention of the Flatusaurus or the Fartceratops.
I'm also wondering if TFNJ's Flatulencian Period was before or after the Paleocene?
Now I understand why the T Rex was so mean! - His "arms" were so short he could hold his nose! (Rim shot)
You all get a vote from me. Very clever.
At the time it was known as a Jurassic Fart.
The Flatulecian Period ended abruptly some 65 million years ago. It wasn't a meteor.
Not a meteor, but a huge blue flame? Could that have blown a hole in the Yucatan?
Take a herd of Brontosi and line them in a circle back to back, and at the right moment light a match, and it is possible to create a 100 mile wide crater, and cause a dino apocalypse.
I have to scientific basis for that theory, just tossing out the possibility.
I love words like "could have" and "can't be confirmed" and we are supposed to call it a scientific finding? Kind of like all the computer models for climate change being called truth and real.
Well, it was deduced from several facts that we know about living animals. The first is that an animal cannot be an obligate herbivore without microbial fermentation (although the article states this is an assumption, it is one that is supported by all the biological evidence that we have available, to posit the dinosaurs were somehow different or evolved their own cellulase is absurd). And the second is that methane output is related to biomass by simple calculations. Life is, after all, chemistry at it's core.
If you can do the same thing with a living cow and it is predictable and accurate, then you can do it with an extinct species too. There are many times in which calculations exist prior to empirical confirmation. Especially in physics and chemistry.
That said, the dinosaurs ruled the Earth for 160 million years. There were climate cycles during this time. 65 million years ago, we have irrefutable proof of a major asteroid impact, as well as some major volcanic eruptions around the same time. We have sketchy evidence for a gradual decline of the dinosaurs prior that time, in which case the event 65 million years ago would have been a coup de grace to their extinction.
Either way, self-induced global warming would no doubt be a minor contributing factor compared to the much larger and much more dramatic events that we know, with certainty, occurred.
Hey everyone look at the big brain on Eric!
Yeah. And he just let the cat out of the bag.
" Either way, self-induced global warming would no doubt be a minor contributing factor compared to the much larger and much more dramatic events that we know, with certainty, occurred."
That is a big brain. All I can think of adding is a "Yeah that's right".
Eric since you mentioned the coincidence in timing between the Chicxulub impact and the Deccan traps eruptions, I don't mean to derail this very humorous thread, but could it be that there is a causal link between the two events? Since the Indian land mass was much further south at that time, 65 million years ago, not yet connected to the rest of what would become Asia yet, and the North American continent was also moving, could it be possible that the gigantic impact in what is now the Yucatan, could have actually caused the Deccan traps eruptions, through a massive wave of antipodal vibration?
The timing of the two events is so close together as to be virtually simultaneous on the geological scale. This alone suggests a possible link. When you consider the almost oppositional locations of the two sites it gets more convincing, at least to my mind.
Does anyone know of a plate-tectonics modeling software package that allows you to "rewind" to a particular time?
If you find one, please let me know.
This reminds me of an urban legend featuring a big dinner of Indian food and a small, sealed bedroom...
This article is so preposterously stupid that I am amazed you would publish it.
This article does stink a bit , (sometimes) ....
It was worth it just to hear from Eric.
Slow Monday huh Alan?
Isn't that a nice pleasant change ....
It's never slow around here. But again, I just couldn't resist...
I'm glad you didn't resist, Alan! The world is far too serious these days. This article has provided ample fodder for much needed humor this week!
It added ample farter.
I agree and call out those criticizing to claim that they knew all this already and didn't need to be informed.
I'm curious how they considered carbon dioxide levels relative to the increased methan levels.
Also, what consideration was given to the the higher sea levels = more sea water = more ability for the oceans to absorb atmospheric gases.
The earlier research about increases in carbon levels pointed more toward the signature of methane than carbon dioxide ... which is why the researchers in that case proposed some sort of gas hydrate release. But in this case, there was no consideration of the mechanisms involved. All they did was look at the levels of methane production associated with plant-eating animals today (due to microbial digestion) and extrapolated that effect to reflect how much meat they think was running around during the days of the dinosaurs. It's actually more of a thought experiment than a paleontological investigation.
There was a similar speculative study about the impact of human colonization on the methane emissions from megafauna that went extinct in the Americas. This was cited in the Current Biology paper. You can look up "Methane Emissions From Extinct Megafauna" by Smith et al. in Nature Geoscience: http://www.nature.com/ngeo/journal/v3/n6/full/ngeo877.html
Facts
Gas - Atomic Weight
N2 - 28
O2 - 32
CO2 - 44
CO - 28
CH4 - 16
C - 12
Methane, CH4, rises into the atmosphere where it facilitates the conversion of Sunlight into infrared heat, and reflects infrared heat energy downward. Which has the strongest effect, the C (carbon) in each gas or the gas itself, elemental carbon does the same infrared conversion, but appears black, and gasses appear transparent.
Burning carbon fuel is the strongest source of chemical energy we widely use, since it so powerful why would assume the opposite is true and suggest that carbon emissions cannot affect the climate.
These powerful physical relationships around carbon are seen in every living form of life on Earth, plant, animals, etc. I cannot be breathing Oxygen, digesting dinner, or seeing carbon everywhere without seeing its relationship to life.
The interaction of Sunlight to break the carbon bonds of CO2 is more amazing than seeing a powerful air plane streak across the sky having passengers unconcerned.
If have intelligence why would we not want to use that intelligence to understand our Earth, our lives.
These are basic facts, and from facts we have questions, and from questions intelligence suggests more questions until all the answers have supportig facts.
If you can figure how the physical chemstry of carbon has not affected Earth's history, I have really long time to wait for your answer.
"...the impact of human colon-ization on methane emissions..." :-)
And as the methane trapping tundra soil thaws, all that methane is being released into the atmosphere, which in time will turn this planet into another Venus.
Hey I knew a girl named Venus - kinda wispy, would blow away in a stiff breeze! (rim shot)
Pat, please don't panic. We may heat up a few more degrees Celsius, but not a few hundred. We currently have 390 ppm CO2; Venus has 950,000 ppm. Venus' atmosphere is also much higher pressure. Venus receives significantly more solar energy than we do as it is closer to the sun. Earth's warming and cooling cycles are mainly driven by Milankovitch cycles (eccentricity, precession, etc.), which regularly cycle about every 100,000 years. We are currently experiencing the 'solar maximum' part of the cycle. We have increased the amount of CO2 in our atmosphere by about 100 ppm (vs. the peak CO2 in the previous few cycles), which may extend/enhance the warm period, but the 'sky is not going to fall'...
That's almost funny, Jay.
The last mass extinction event (the PETM, about 55 million years ago) involved a temperature rise of 5C over the course of 20,000 years.
We're currently on track to do the same thing in less than 250 years. While we won't become another Venus, Pat is right to be concerned about this - far more right than your 'don't worry, everything's fine' post is.
I agree on the worry. A run away effect is what should be considered.
Physicist, how much warming is due to man-made GHG and how much is due to where we are in the Milankovitch cycle? We don't know. Temperature rises preceed CO2 release during such cycles, as less CO2 dissolved in warmer water (and methane released from thawing permafrost, etc.). Have global warming models included the affects of the Milankovitch cycle?
TFNJ, a 'run-away effect' is even less of a concern. Eventually, after the 'peak warming' of the Milankovitch cycle, and the Earth begins to cool, CO2 will be re-absorbed into the oceans and polar cap freezing expands (increasing the albedo of the Earth and enhancing the 'cooling period'). Mind you, this is a 100,000 year cycle, so things tend to change slowly. I'm not saying that we won't have ill effects from the extra 100 ppm CO2 (or the probable 50-100 ppm more that we will belch into our atmosphere before migrating towards non-GHG producing alternative energy production). However, please keep the superlatives in check. The low points in the Milankovitch cycle are about -8 degrees Celsius from our current mean global temps. I'm an avid hockey fan, but I'd rather be living during this 'warm period'.
Yes, we do.
Anthropogenic and natural warming inferred from changes in Earth’s energy balance (2011)
Much, much more research available on that topic (radiative forcings - that's us).
No, it doesn't:
Global warming preceded by increasing carbon dioxide concentrations during the last deglaciation (2012)
Try Google Scholar to keep up with the research, Jay. Otherwise, you may be left with talking points that are seriously outdated.
On a side note, climate scientists discovered Milankovitch cycles. They are quite aware of the impacts those cycles have on our climate - indeed, climate scientists are the reason that you know anything about those cycles at all.
Physicist, thanks for the link regarding the last deglaciation. I'll take a look at it. Everything I've read about the analysis of the Vostok ice cores (over 400,000 years worth of history), point to temperature increases preceeding CO2 increases by several hundred years. It's a key point. But can we please put to rest the hysteria over 'becoming like Venus' and 'runaway greenhouse effect'?
I about spewed Pepsi through my nose reading this! At first, I thought it had to be a joke but... it's not April 1st and looking over the global warming crowd, I could see how this kind of ridiculousness could get some traction...
Maybe we should all go out and eat a cow to save the earth now?
Make mine a ribeye, medium rare, please... lmao!
The carbonated beverage you were drinking contains CO2, and may have a affected your thinking.
I said it a few months back. What about the dinosaurs and all that crap and other body functions. If it did not cause global warming, we sure as hell with animals are not!
I heard there was a T. Rex on the Ark that could burp the whole first half of Genesis
And when the teenage male dinosaurs got together they would worsen the affect by farting over a live volcano, creating massive firestorms that could be seen for miles by the adult dinosaurs, causing them to shake their heads and think "Extinction's not comming soon enough".
Robert - I love it. Great one!
I can add - Jezz, he's just like is Father!
Very nice! LOL. A serious issue and lots of ignorance but this is funny. I heard the same thing. Ya:)
Your science stinks.
Whether or not Dinosaur methane really contributed significantly to global warming, it is clear that the earth has been both much warmer and much colder at different periods in the past, and will likely be so in the future. Too little attention has been paid to the fact that slightly increasing carbon dioxide levels occurring in the atmosphere today may actually be a GOOD thing, since they will likely promote more plant growth resulting in a further 'greening" of the planet and making it possible to feed even larger animal populations. We currently know too little to be sure whether the current warming trend is a good or a bad thing. While it would be wise to reduce our dependence on fossil fuels to avoid dumping increasing levels of such pollutants as sulfur dioxides, carbon monoxide, mercury, lead, thorium, and uranium in the fly ash from coal powered plants, I see no particular reason to believe that it is necessary to limit the emission of carbon dioxide or methane per se.
And people shouldn't quit smoking, because it's actually a good thing when they become sick, as it creates work for doctors, and when they die, it makes room for more new people.
Whether man-made global warming is occurring or not, no sensible person could actually say that limiting our dependence on fossil fuels for the purposes of economic stability and decreased environmental pollution would be a bad thing. Anyone that does is either a straight up idiot, or has a deliberately destructive personality.
Yeah, throwing trash out of your car window employees those guys on the side of the road in those orange vests and "pick up" sticks. Committing murder and burglaries employees cops. Arsonists help keep firemen and insurance agents in business.
Bad things employee good people.
As to your:
too much of a good thing is not always good. Read about the fertilizer runoff creating algae blooms that, though increasing nutrients for algae, actually causes the mass death of other sea and freash water creatures due to decreasing oxygen levels.
@tony- And the promotion of plant growth in some places means a reduction in other places and eventually most places. The windfall won't go on forever.
I welcome those who were outraged by my comment above to consider reading the very lucid and thought-provoking new book by Dr. Robert Zubrin entitled "Merchants of Despair: Radical Environmentalists, Criminal Pseudoscientists, and the Fatal Cult of Antihumanism."
Of course, or at least a changing of the plants in an environment. Just like the change in plant species going up a mountain is similar to the change in species moving north in latitude, if the globe is warming we will see species of plants "migrating" further north, and south in the Southern Hemisphere.
As if the flatulence of 7 billion humans didn't affect anything...
I was watching a pod of manatees in the Florida Keys one day ....
And one of them released enough gas ....
That it appeared like a scuba diver was down there ....
From the amount of bubbles boiling up for so long ....
So by this occurring all the time from both land and sea creatures , including birds ....
That would be a whole lot of emitted gas ....
And possibly worthy of some serious study ....
But not by me .... "LOL"
Always fun on the "Cosmic Log" ....
Thanks Alan Boyle ....
LOL...
Silence and deadly...
If we ate more meat, we would have less greenhouse gasses. Veg-heads want us to eat less meat so we can have more global warming. Veg-heads are anti-humans.
Vegetarians would be more anti-human if they were more direct in their dietary choices, but as I understand vegetarians that have the goal of stretching the food supply to accommodate more humans. This must come to some conclusion differing from the simple consequences. Stretching the food must imply that more humans are better for the planet, I assume more intelligent beings could see the value of living well, but then allowing more humans may allow time for them to evolve, more intelligence. Then it could be true that this is it, that we have evolved as far as we can, so by allowing more time for human to evolve could lead them to more pastoral ways. This makes more sense that assuming the relentless inbreeding will produce a being intelligence enough to see that inbreeding, has already produced damaged goods or more directly that having genes for intelligence will survive better than being intelligence or using intelligence. This intelligence only appears from time to time, when the species is threatened, because if intelligence was dominant that it would impair reproduction. The human animal appears to have reached a dead-end, because human genes do not have the capacity to evolve away from the dead-end, and hence are "terminal species". The growth of top predator depends on not reproductive success, but on an unlimited supply of things to eat.
Homo sapiens is still evolving, as selection is still strong in certain areas of the world and it is not the only force that contributes to evolution in the first place.
But yes, your basic statement is correct - our population has expanded to the point where further dramatic evolution will most likely be at our own hands.
We've only deceived ourselves into believing we are the top predator. In reality, we have merely isolated ourselves from nature and found comfort in the areas of it that we can control. Take a stroll through the savannahs of Africa or the Amazon Rainforest with no prior knowledge of how to evade the dangers there, and you will find that we are far from being the most deadly or efficient predator on this planet.
Not precisely, humans are on their last legs as far as significant evolution goes, when consider the genetic paradigm (replicate (genes), differentiate (genes)). This occurs over very long period of time, with strong preference to accumulate genetic variety, when this accumulation begins to differentiate is allowing the number of species and varieties then evolve. Humans have had their day simply because their size precludes changes. ...
The humans are the top predators, simply because human mine minerals, and energy sources and using inventions are within reach of killing off the Rain Forest, and pploughing up the Savanna. This is not hand to hand combat were the creatures spit out bullets, or the human pack animal gives up territory, and does so most effectively, since efficiency is not part of the human energy equation right now. Human evolution is not "Survivor".
Humans continue to evolve, but with increasing diversity, not as a homogeneous population. Humans are capable of selecting the most desirable traits in their mates, but less desirable genes will also survive within the population.