Guest commentary by David Middleton
From the No Schist Sherlock files…
PUBLIC RELEASE: 19-APR-2018
Humans have been driving a global reduction in mammal size for thousands of years
AMERICAN ASSOCIATION FOR THE ADVANCEMENT OF SCIENCE
The dispersal of humans out of Africa coincided with a dramatic global reduction in the size of mammals, a new study reveals. This “downsizing” trend may continue, suggest the authors, to the extent that, in just a couple hundred years, the largest terrestrial mammal left may be the domestic cow, weighing in at 900 kilograms (kg). Felisa A. Smith et al. sought to understand how the size of mammals has changed over time. They updated and created two datasets that capture the global distribution and body size of terrestrial mammals that lived between 66 million years ago through the present. The authors found a substantial bias in mammal extinction during the periods when humans were dispersing around the globe, whereby species that went extinct tended to be two to three times bigger than mammals that survived, a trend that was evident globally. Notably, prior to humans’ migration out of Africa 125,000 years ago, Africa was home to mammals of smaller size (with a mean body mass roughly half that of mammals found in Eurasia), which the authors suggest is reflective of the hominin-mammal interactions that had already been at play. Perhaps most striking is the reduction of mammals in the New World during the late Pleistocene, which coincided with humans’ adoption of long-range weapons. The authors report a greater than 10-fold drop in both mean and maximum body mass of mammals during this time; for example, mean mass of terrestrial mammals in North America fell from 98.0 to 7.6 kg. If current trends continue, the mean body mass of mammals in North America will drop from 7.7 to 4.9 kg in a few hundred years, the authors say. As mammals play a critical role in shaping ecosystems, the downsizing trend will have a cascading impact on other organisms.
The paper is pay-walled. Here are a few highlights from the abstract:
- Today, it is well known that human activities put larger animals at greater risk of extinction.
- If the current trend continues, terrestrial mammal body sizes will become smaller than they have been over the past 45 million years.
- Since the late Pleistocene, large-bodied mammals have been extirpated from much of Earth.
- This decline is coincident with the global expansion of hominins over the late Quaternary.
- Moreover, the degree of selectivity was unprecedented in 65 million years of mammalian evolution.
- The distinctive selectivity signature implicates hominin activity as a primary driver of taxonomic losses and ecosystem homogenization.
And my comments on the highlights:
- They were in the way, some of them hunted us and most of them tasted good.
- Where do you think Chihuahuas, Pomeranians and Corgis came from? Besides, when was the last time a large mammal species became extinct? What percentage of megafauna bought the farm in the Early Holocene vs the fictitious “Anthropocene”?
- I’m sure we didn’t intend to extirpate most of them. My guess is that most of them were long gone before the word “extirpate” was invented. It’s highly likely that our ancestors used the word “eaten” in the early days of language.
- Are you saying we should have stayed in Olduvai Gorge? Or that we should have extirpated ourselves?
- Blame the dinosaurs. If they didn’t get extirpated. none of this would be happening.
- So what?
Is “the bleeding obvious” really a scientific discipline? Humans played a big role in wiping out 169 out of 244 genera of mammalian megafauna from the Late Pleistocene through the Early Holocene. This isn’t a eureka-worthy new discovery:
Here’s another gem from the Eureka Alert article:
Perhaps most striking is the reduction of mammals in the New World during the late Pleistocene, which coincided with humans’ adoption of long-range weapons.
What’s even more striking than most striking is that it was also coincident with human domestication of wolves. Dogs may have played an integral role in enabling humans to out-compete Neanderthals. Humans began the process of shrinking wolves between 20,000 and 40,000 years ago.
New data from ancient dogs indicates that dogs became distinct from wolves between 20,000 and 40,000 years ago, researchers report July 18 in Nature Communications.Dogs then formed genetically distinct eastern and western groups 17,000 to 24,000 years ago, the researchers calculate. That timing and other genetic data point to dogs being domesticated just once.
As early as 10,000 years ago dogs in the Americas were so valued as companions and fellow hunters that at least three of them were given proper burials rather than being eaten:
WASHINGTON — A trio of dogs buried at two ancient human sites in Illinois lived around 10,000 years ago, making them the oldest known domesticated canines in the Americas.
[…]
Ancient dogs at the Midwestern locations also represent the oldest known burials of individual dogs in the world, said Perri, of Durham University in England. A dog buried at Germany’s Bonn-Oberkassel site around 14,000 years ago was included in a two-person grave. Placement of the Americas dogs in their own graves indicates that these animals were held in high regard by ancient people.
An absence of stone tool incisions on the three ancient dogs’ skeletons indicates that they were not killed by people, but died of natural causes before being buried, Perri said.
[…]
So… Yes, “humans have been driving a global reduction in mammal size for thousands of years” and it had nothing to do with fossil fuels, CO2 or Gorebal Warming… Nor would renewable energy sources or a Tesla in every garage have prevented it.
Some of the big mammals wound up here:
And some wound up here:
The moral of the story: Big animals that chose to help us hunt fared better than those that didn’t.
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Ye, this is called “evolution”, you creationist morons.
Nature is a cruel mother, and stand by the “Vea Victis” motto (aka “eat or get eaten”). And Humans are the victor, and all other animals AND vegetal unfortunate enough to compete against humans (that is, pretty much anything weighting more than ~5kg) are the loser.
Obviously they wont survive unless humans turn him into some sort of pet or slave.
But don’t worry. Humans are themselves out-competed by their own creation, those artificial beings we call states and corporations, and themselves won’t survive long.
Have fun
Not that I am a ‘creationist’ but creation, or the origin of life, and evolution, i.e. what happened to life along the way, have nothing to do with each other.
While you are pondering the moment a man was created by God (another individual), I was wondering how it was possible for a self-replicating molecule in a dilute soup to assemble itself in a survivable form. Your miracle, my miracle.
On the other hand, the common cold viruses, various flu viruses, and various bacterial disease have proliferated by feeding on US!
News Flash: For the last 100 years humans have been causing electronic devices to shrink. Film at 11.
+1,000
Honey, I shrunk the dog.
What’s next?
Pyrites of the Caribbean were actually gneiss?
Oh… That’s some good schist.
You’re just being a sillimanite.
More bizarre anti-human pap.
What does the average size of mice and elephants represent?
You have to use anomalies to average them.
+1
Obviously, this “study” didn’t look at city-dwelling rats, some of which get as big as cats. :-O
I am a mammal and I am expanding at a great rate.
I accidentally ran over a rat, this morning. On my way home from a nightshift.
I did look in my rear view mirror, and it definitely looked smaller. Or at least, flatter.
Then again, rear view mirrors do make objects look smaller.
And then we must take account of the effects of perspective as I drove away from the crime scene.
This is not really very scientific, but I will take solace in the fact that it all looks like an exacting experiment compared to an attempt to reconstruct the global average temperature at one point in time – from the behaviour of just one tree.
Progressives might have to make a decision: at what stage of human development did we become evil, and who are the people today who are supposedly less evil? Is any use of tools bad? I like the story that the more they look at the Amazon, the more they think that at the time of European contact, the forest was not truly wild; to some extent it was farmed or managed. That’s what the big brains are for.
The three heifers I raised last summer didn’t shrink: I bought them at ~800 lbs each last spring and by the end of last year they produced 2,140 lbs of prime beef, all cut and wrapped.
I know at least a dozen human animals, all customers of that beef, who also aren’t shrinking!
There are proposals to try to recreate mammoths and the like. It is probable some of my ancestors found them yummy.
Damn Straight Skippy. Humans didnt spend millions of years evolving into the apex predator on planet Earth to eat tofu.
LOL. That’s more the result of the emaciation of brain matter that results from “low-fat diets” and other such junk science-based “fads.”
This “study” didn’t do its homework. The smaller the animal, the lower the liklihood that we, today, will find any remants to study. The effect is proportionate to size. We have many more records of larger animals than smaller, so of course it will appear that larger animals disappeared faster. Did humans have an effect? Most likely yes. The bigger the animal, the bigger the payoff for a successful hunt. Also, there isn’t much macho in collecting a ton of rats, and they have a much poorer carcass yield(% of edible compared to overall weight). Cows average about 65%, depending on age and weight, chickens are more uniform at about 75% and produce 1 lb of meat for every 2.5lb. of feed. Cows require about 7lb of feed per pound of meat. When you get down to really small mammals such as rats the yield is much less and requires an immense amount of work.
Capybara, the world’s largetst rodent at around 80kg has been hunted nearly to extinction. It would be a good candidate for a meat animal but for the fact that it’s preferred habitat is shallow swamps.
Capybara clever beast. Prefers swamps because humans don’t.
Or perhaps the savanna capybara wasn’t fast enough? 😉
” The smaller the animal, the lower the liklihood that we, today, will find any remants to study”
Nope. Microfaunal sites and remains are usually more common than megafauna.
Humans are getting larger……
https://www.scientificamerican.com/article/why-are-we-getting-taller/
From eating all those tasty megafauna!
Just ain’t buying it, never have. First why didn’t humans drive megafauna in Africa to extinction prior to out migrating. Had an anthropology professor who was selling this hypothesis back in the 1960s about the Americas. Her understanding was a bit bizarre. She somehow had concluded that humans were extremely abundant at the time they arrived in the America like some flood and then they went around willy-nilly slaughtering megafauna in some blood feast. Even then she believed that male human were the personification of evil and responsible for all the problems in the world, if women were in charge none of the megafauna extinctions would have happened. Even though she accepted the ice/ land bridge hypothesis as to how humans arrived in the Americas she really believed that the climate was stable after humans arrived in the Americas so it couldn’t have possibly been a change in climate that caused megafauna extinction.
There actually was a number of extinctions in Africa about 100,000 years ago. But remember that Homo sapiens evolved in Africa so the fauna had time to adapt. In the rest of the world Homo sapiens arrived suddenly and encountered a fauna that had either only experience of less efficient hunting hominids (Eurasia) or non at all (America, Australia).
And as for the “change in climate” hypothesis. Isn’t it rather odd that the changes happened at different times in different places, but always just after the first humans arrived?
tty, What mass extinctions in Africa? Do you hunt? Have you ever hunted megafauna? Have your ever hunted with a stabbing spear, throwing spear, atlatl, wooden bow, all with stone points, etc? Species go extinct and the vast majority of the time it has absolutely nothing to do with humans hunting for food which was the excuse my professor and others have made for mass extinctions. And why hunt megafauna in the first place? Extremely dangerous since one has to get up pretty close and personal with a “primitive weapon.” The whole hypothesis is flatly just another progressive fantasy blaming all humans from the beginning of time for all problems. Funny, those promoting such hypotheses never see themselves as the evil ones, just everyone else.
Eating isn’t evil. And, oddly enough, the extinction that took out the megafauna isn’t classified as a mass extinction.
Wasn’t there a rise in temperature during that period? With a big jump some 12Kyr ago?
“when was the last time a large mammal species became extinct?”
About 2002, Chinese River Dolphin Lophotis vexillifer.
Not exactly large…
And not exactly extinct…
https://www.theguardian.com/world/2016/oct/11/china-extinct-dolphin-returned-yangtze-river-baiji
By the way would you accept the Caribbean Monk Seal Neomonachus tropicalis as “large” (8 foot, 500 pounds) and extinct (last seen in 1952)?
Borderline large. Placed on the endangered species list 15 years after it supposedly went extinct…
https://en.wikipedia.org/wiki/Caribbean_monk_seal
Do Monk seals really rate two genera and three species (2 extant and 1 currently extinct)?
If the Monk seals had all snuffed it in the Late Pleistocene, would their fossils be recognized as two genera and three species? It strikes be in the same way that dog breeds have been declared extinct.
https://climate4kids.blogspot.com/2014/08/when-extinction-isnt.html
Animals declared extinct and later found to have fooled the scientists.
Rather like the Ivorybilled woodpecker in “revived” every decade or so, but unfortunately always without any proof…
Once an animal is declared extinct, there is no longer any need for the EPA to protect it’s habitat.
That can’t be allowed.
Next, and soon, will be the North Atlantic right whale.
“If the Monk seals had all snuffed it in the Late Pleistocene, would their fossils be recognized as two genera and three species?”
They would certainly be recognized as separate species since they are osteologically distinct. Whether they would be regarded as two genera is more uncertain. This is based on DNA studies that show that while Caribbean and Hawaian Monk Seals have been isolated since the Panama gateway closed about 3-4 million years ago the separation from the Mediterranean species dates back to the Miocene 6-7 million years ago. That means that the Hawaian/Caribbean and Mediterranean Monk Seals are about as different genetically as humans and chimpanzees.
The Northern White Rhino is on the brink. If not over it. I’m not sure if every biologist would consider it a distinct specie.
The question was in response to this:
And it was a multi-part question:
I wasn’t challenging the fact that some large mammals have gone extinct in the recent past or will go extinct in the near future.
I was pointing out that not all of the reduction in mammal size was due to extirpation and that most of the mammalian megafauna extirpation occurred well-before the fictitious geologic time period known as the “Anthropocene.”
Regarding the White Rhino… color is not a species.
I thought the White Rhino was named after the European dude who first documented it.
It is actually thought to be an Anglicization of the Dutch “wijd”, meaning wide. White rhinos have wide square mouths while black rhinos have a pointed upper lip. The former are grazers and the latter are browsers.
Northern white rhinos are considered a subspecies. There is some argument as to whether it is its own species, but that is probably true of most species.
Scientists were going to attempt to harvest ova from the northern females last month, the ultimate goal is IVF with banked sperm from now deceased males. The embryo would be placed in a southern white female who is living with the northern white females. The idea is for the calf to be behaviorally and socially influenced by the northern females. We will see what happens…
Where’s the mention of Climate Change? Stripped of the “models predict”, “as climate continues to change” and “worse than we thought”, etc. etc., these scientific articles are beginning to get back to a recitation of observations. Which is what they should be.
But it also makes them look rather diaphanous (thin, flimsy, of little substance, easy to see through). I do like that word. I’m going to start using it in technical reports where I need to portray publications containing opposing hypotheses in a negative way.
Oh… There was a model involved…
http://science.sciencemag.org/content/360/6386/310
Most of the really large land animals come from Africa, the place where humans also come from and presumably the place where the two groups have interacted the most and for the longest period of time.
This is the big weakness that sinks this particular theory.
Not at all, most of the surviving really large animals are in Africa.
Not so long ago for example there were elephants in all continents except Australia and lions in all continents except Australia and South America (and there was a “Marsupial Lion” in Australia).
All you have done is repeat my point. The surviving ones are in the area that is the most impacted by humans.
Actually Africa is the continent least impacted by humans though inhabited for the longest time. Until very recently it was very sparsely inhabited and much less affected by agriculture than the other continents.
Once again, that’s my point.
Also, all continents were sparsely populated by humans until relatively recently.
What a pity that sabre-toothed tigers are gone.
They seem to have largely hunted young mastodons and mammoths so it’s not very surprising that they are extinct.
In Eurasia they became very rare already in the Middle Pleistocene but they apparently survived in small numbers until c. 40,000 years ago. In other words they went extinct at about the same time as the Neanderthalers.
Not to mention the short faced cave bear.
The Short-faced Bear and the Cave Bear were different species in different genera on different continents.
There is really no doubt that human selection by hunting (and fishing) has a strong effect on animal size. There is however a climatic effect at work as well. Most animals “shrink” during interglacials compared to glacials, and this is noticeable during previous interglacials as well, when no Homo sapiens were present.
Makes you wonder if some of them might recover from extinction during the next glacial stage… /sarc
That was an exceptionally silly remark /not sarc
Makes me wonder if Homo are smaller now than during the last glacial? But as far as I know, people don’t follow Bergman’s Rule very well, so perhaps not.
But not until humans invented gunpowder and guns to use it in …. and monster fishing nets and harpoons deployed by men in boats.
Excerpted from “public release” portion of above commentary, to wit:
“DUH”, an associated “coincidence” is not proof of causation.
NOTE: the late Pleistocene includes the last interglacial–glacial cycle ending at the Holocene boundary about 11,700 years ago.
So saidith David Middleton, to wit:
Now humans might have played a minor role in the global reduction in mammal size during the past 20 thousand years, ….. but there is no factual or scientific evidence to support that conjecture.
“HA”, native Americans had been using “long-range weapons” for thousands of years but the great herds of Bison suffered no ill effects from said “hunting pressure”.
And David M, you didn’t specifically say so, but I assume your above claim of ….. “had nothing to do with CO2” ….. that you were actually inferring, to wit: ….. “had nothing to do with increasing atmospheric CO2”, ….. which I agree with.
But, ….. in actuality, …… the global reduction in mammal size during the late Pleistocene (pre-Holocene or prior to 11,500 YBP) was the direct result of atmospheric CO2, ….. a DECREASE in CO2, …. not an INCREASE in CO2.
Atmospheric CO2 ppm began steadily declining about 145 MYA when it was at 2,000 ppm. And at 66 MYA the CO2 was at around 600 ppm and the dinosaurs had mostly all perished. And by 11,500 YBP the CO2 had decreased to less than 200 ppm which caused the demise of most of the remaining large carnivores as the result the demise of large herbivores.
I meant to include this graph in the above post, to wit:
Source ref: https://globalfreezingyourassoff.wordpress.com/2016/12/30/the-grim-reality-of-ice-ages/
Samuel, I am still hung up on their “during the late Pleistocene, which coincided with humans adoption of long-range weapons.” What the heck long range weapons are they talking about? English Long Bow? Modern Compound Bow? I doubt that during the Pleistocene a primitive bow would shoot more than a couple of hundred yards but wouldn’t effectively kill at much over 50 yards. Atlatl maybe a max of 70 yards with a kill radius of also less than 50 on a good day. I doubt that neither a bow nor an Atlatl could kill a heavy skinned megafauna even at fifty. In stone tip projectiles they had a huge investment so they would get as close as possible to ensure a kill. I am betting even at the end of the Pleistocene the world human population was not much over 10 million humans.
The human brain has shrunk 25%, so we are our own victims.
Maybe it’s just a relative optical illusion.
Any sandwich made from her would have way too much fat in it.
Why does she want to be a sandwich?
She wants to be useful?
Actually, it would probably have too much bread and added sugar in it. You don’t get that way by eating fat – quite the reverse, in fact.
Obi-Wan never told you what happened to your mother.
Or maybe it’s just that the remains of larger mammals are more commonly found for periods farther back in history. The larger the mammal the more likely its skeletal remains are somewhat intact and discovered.
Very dubious. Microfaunal remains are normally more common than megafauna. It might be true for elephants which have very robust skeletons (particularly teeth and tusks) that are also easily noticed by laymen.
One would think that there is a fairly strong bias towards large vertebrate animals in fossil reconstructions for several reasons. For example, large is easier to find, probably to be preserved in the first place (teeth may be an exception), and more likely to attract the attention of a palaeontologist, at least until recent decades. In general, large animals are rarer than small ones, but tend to have broader distributions. So, I think it is quite reasonable to expect a bias towards larger vertebrates in the fossil record, at least as a proportion of the taxa known, that has made it into the literature. I suppose this hypothesis could be tested by comparing the number of known small to large fossil ‘species’ within a group to recent faunas.
Not sure about 66 mya but certainly 66 thousand ya…just about every culture on the planet has a “Great Starvation” story in their oral history. Much more energy efficient to kill and eat a Giant Three toedSloth than a rabbit or squirrel. The North American Megafauna were hunted to extinction by the First People’s.
Wharfplank, I don’t see why first people would prefer to hunt a mastodon instead of going fishing or snaring bunnies….dangerous stuff that, and a lot of work….I think it much more likely that those first people’s dog’s fleas infected the megafauna with diseases that killed them off rather quickly.
And yet, despite it all, we humans coexist with the Blue Whale (balaenoptera musculus), which is the largest animal to have ever existed on this planet as far as we know.
I suspect this is so because historically our habitats have not significantly overlapped until rather recently. But, when they did the cetaceans weren’t winning. Luckily, they seem to have survived the period where our technology surpassed our need for their body oils.
Goodness, lets not head back that way again.
I think, at least in part, the Blue whales and Sequoias were spared to a large extent for the same reason. They are so damned big the limited technology of the time available to harvest and process them just made it so it didn’t make a lot of economic or practical sense as long as there were enough of smaller species that fit the need. That is not to say that both weren’t harvested for a time. But in the case of the Blue Whale it was not like they knew their migration patterns and where to find congregations of them at certain times of the year as they did the others. We still don’t. How do you deal with an animal who’s tongue weighs as much as an elephant?
“Perhaps most striking is the reduction of mammals in the New World during the late Pleistocene, which coincided with humans’ adoption of long-range weapons.”
Would that be the assault atlatl?
https://en.wikipedia.org/wiki/Spear-thrower
With a high capacity quiver!
Were those fully semi-automatic assault atlatls?
I think we may need to ban them. Or at least require background checks and waiting periods.