Some of my friends at work are baseball fans. I totally don’t get baseball – to me, it’s about as interesting as watching paint dry. But thankfully, some of my friends disagree, which is how I found this lovely little bit of crackpottery.
You see, there’s a (former?) baseball player named Jose Canseco, who’s been plastering twitter with his deep thoughts about science.
Ancient gravity was much weaker
— Jose Canseco (@JoseCanseco) February 19, 2013
You ever wonder why nothing REALLY big exists today in nature
— Jose Canseco (@JoseCanseco) February 19, 2013
elephants today eight tons supersaurs two hundred tons a totally different world. why?
— Jose Canseco (@JoseCanseco) February 19, 2013
Animal tissue of muscles and ligaments could not support huge dinosaurs even standing up or pump blood up 60 foot necks
— Jose Canseco (@JoseCanseco) February 19, 2013
Gravity had to be weaker to make dinosaurs nimble
— Jose Canseco (@JoseCanseco) February 19, 2013
My theory is the core of the planet shifted when single continent formed to keep us in a balanced spin
— Jose Canseco (@JoseCanseco) February 19, 2013
The land was farther away from the core and had much less gravity so bigness could develop and dominate
— Jose Canseco (@JoseCanseco) February 19, 2013
I may not be 100% right but think about it.How else could 30 foot leather birds fly?
— Jose Canseco (@JoseCanseco) February 19, 2013
At first glance, this is funny, but not particularly interesting. I mean, it's a classic example of my mantra: the worst math is no math.
The core of this argument is pseudo-mathematical. The dumbass wants to make the argument that under current gravity, it wouldn't be possible for things the size of the dinosaurs to move around. The problem with this argument is that there's no problem! Things the size of dinosaurs could move about in current gravity with absolutely no difficult. If you actually do the math, it's fine.
If dinosaurs had the anatomy of human beings, then it's true that if you scaled them up, they wouldn't be able to walk. But they didn't. They had anatomical structures that were quite different from ours in order to support their massive size. For example, here's a bone from quetzlcoatlus:
See the massive knob sticking out to the left? That's a muscle attachement point. That gave the muscles much greater torque than ours have, which they needed. (Yes, I know that Quetzalcoatlus wwasn't really a dinosaur, but it is one of the kinds of animals that Canseco was talking about, and it was easy to find a really clear image.)
Most animal joints are, essentially, lever systems. Muscles attach to two different bones, which are connected by a hinge. The muscle attachement points stick out relative to the joint. When the muscles contract, that creates a torque which rotate the bones around the joint.
The lever is one of the most fundamental machines in the universe. It operates by the principal of torque. Our regular daily experiences show that levers act in a way that magnifies our efforts. I can't walk up to a car and lift it. But with a lever, I can. Muscle attachment points are levers. Take another look at that bone picture: what you're seeing is a massive level to magnify the efforts of the muscles. That's all that a large animal needed to be able to move around in earths gravity.
This isn't just speculation - this is stuff that's been modeled in great detail. And it's stuff that can be observed in modern day animals. Look at the skeleton of an elephant, and compare it to the skeleton of a dog. The gross structure is very similar - they are both quadripedal mammals. But if you look at the bones, the muscle attachment points in the elephants skeleton have much larger projections, to give the muscles greater torque. Likewise, compare the skeleton of an american robin with the skeleton of a mute swan: the swan (which has a maximum recorded wingspan of 8 feet!) has much larger projections on the attachment points for its muscles. If you just scaled a robin from its 12 inch wingspan to the 8 feet wingspan of a swan, it wouldn't be able to walk, much less fly! But the larger bird's anatomy is different in order to support its size - and it can and does fly with those 8 foot wings!
That means that on the basic argument for needing different gravity, Canseco fails miserably.
Canseco's argument for how gravity allegedly changed is even worse.
What he claims is that at the time when the continental land masses were joined together as the pangea supercontinent, the earths core moved to counterbalance the weight of the continents. Since the earths core was, after this shift, farther from the surface, the gravity at the surface would be smaller.
This is an amusingly ridiculous idea. It's even worse that Ted Holden and his reduced-felt-gravity because of the electromagnetic green saturn-star.
First, the earths core isn't some lump of stuff that can putter around. The earth is a solid ball of material. It's not like a ball of powdered chalk with a solid lump of uranium at the center. The core can't move.
Even if it could, Canseco is wrong. Canseco is playing with two different schemes of how gravity works. We can approximate the behavior of gravity on earth by assuming that the earth is a point: for most purposes, gravity behaves almost as if the entire mass of the earth was concentrated at the earths center of mass. Canseco is using this idea when he moves the "core" further from the surface. He's using the idea that the core (which surrounds the center of mass in the real world) is the center of mass. So if the core moves, and the center of mass moves with it, then the point-approximation of gravity will change because the distance from the center of mass has increased.
But: the reason that he claims the core moved is because it was responding to the combined landmasses on the surface clumping together as pangea. That argument is based on the idea that the core had to move to balance the continents. In that case, the center of gravity wouldn't be any different - if the core could move to counterbalance the continents, it would move just enough to keep the center of gravity where it was - so if you were using the point approximation of gravity, it would be unaffected by the shift.
He's combining incompatible assumptions. To justify moving the earths core, he's *not* using a point-model of gravity. He's assuming that the mass of the earths core and the mass of the continents are different. When he wants to talk about the effect of gravity of an animal on the surface, he wants to treat the full mass of the earth as a point source - and he wants that point source to be located at the core.
It doesn't work that way.
The thing that I find most interesting about this particular bit of crackpottery isn't really about this particular bit of crackpottery, but about the family of crackpottery that it belongs to.
People are fascinated by the giant creatures that used to live on the earth. Intuitively, because we don't see giant animals in the world around us, there's a natural tendency to ask "Why?". And being the pattern-seekers that we are, we intuitively believe that there must be a reason why the animals back then were huge, but the animals today aren't. It can't just be random chance. So people keep coming up with reasons. Like:
- Neal Adams: who argues that the earth is constantly growing larger, and that gravity is an illusion caused by that growth. One of the reasons, according to his "theory", for why we know that gravity is just an illusion, is because the dinosaurs supposedly couldn't walk in current gravity.
- Ted Holden and the Neo-Velikovskians: who argue that the solar system is drastically different today than it used to be. According to Holden, Saturn used to be a "hyperintelligent green electromagnetic start", and the earth used to be tide-locked in orbit around it. As a result, the felt effect of gravity was weaker.
- Stephen Hurrell, who argues similarly to Neal Adams that the earth is growing. Hurrell doesn't dispute the existence of gravity the way that Adams does, but similarly argues that dinosaurs couldn't walk in present day gravity, and resorts to an expanding earth to explain how gravity could have been weaker.
- Ramin Amir Mardfar: who claims that the earth's mass has been continually increasing because meteors add mass to the earth.
- Gunther Bildmeyer, who argues that gravity is really an electromagnetic effect, and so the known fluctuations in the earths magnetic fields change gravity. According to him, the dinosaurs could only exist because of the state of the magnetic field at the time, which reduced gravity.
There are many others. All of them grasping at straws, trying to explain something that doesn't need explaining, if only they'd bother to do the damned math, and see that all it takes is a relatively small anatomical change.
I don’t think you’ve answered the basic problem: the absence of huge creatures. Yes, it’s great that you can talk about torque and bone structure and how this permitted them to exist under perfectly normal… but such bone structure and torque can exist *now* too, so this is at best a refutation of their explanation and not a correct explanation.
(Extra oxygen in the atmosphere? Humans hunting to extinction all large creatures?)
There doesn’t have to be a reason beyond randomness. There are many different directions that evolution can go, and which one(s) become dominant at any point in time are, in large part, random.
At some point in time, some mutations made creatures larger, and their size gave them an advantage. Repeat that cycle many times, with slightly larger creatures getting an advantage, and over millions of years, you wind up with many large creatures.
They got wiped out by climate changes caused by an asteroid. The size thing just randomly hasn’t reoccurred. There are many kinds of creatures in the world today that weren’t around in the time of the dinosaurs. Why were there no mammals then? Because mammals hadn’t evolved in that environment. Why aren’t there dinosaur-sized creatures today? Because they haven’t evolved in todays environment.
I do seem to remember reading once that dinosaurs were able to evolve to the size they were back then because atmospheric oxygen content was much higher than it was now (26% as opposed to 20% according to wikipedia.) Those big muscles need more oxygen.
Oxygen gets absorbed at the lung-blood interface which is a surface (which is why lungs are very wrinkly if you zoom in far enough, more surface area.) If one were to simply scale up an organism (which Mark made clear is an oversimplification) this surface area would scale up to the second power, while the volume of tissue requiring oxygen scales to the third power, as you scale your oxygen supply will not be able to keep up with your mass.
While this could be compensated for by adaptations for extra oxygen or more efficiency, a bit of extra oxygen in the air helps as well.
Of course, my explanation here is overly simplistic (if not plain wrong) as well, reality is always more complex!
I don’t believe the relation you suggest between lung volume and useful area holds. Lungs have a fractal structure, not a smooth one, and their fractal dimension is near to 3. I didn’t found a good justification in a few seconds, but you’ll get the idea:
http://library.thinkquest.org/26242/full/ap/ap11.html
That’s just the expected. If you double the volume, you can put there more foldings, interchanging more oxigen.
In fact, probably big animals consume less oxigen per unit of mass than small ones. Just thing about the economy of scale!
“There doesn’t have to be a reason beyond randomness.”
Well, there certainly doesn’t have to not be a reason. I think what the other commenters are asking is, what are the selection pressures that favor gigantism? Just because you don’t know what they are doesn’t mean they never existed.
“the absence of huge creatures”
What absence? The largest animal ever known to have lived is the blue whale; there are still some alive today.
Mr. Canseco must have read my theory, ‘The Gravity Theory of Mass Extinction’ which explains how the core elements shifted. The law of conservation of angular momentum cannot be violated. When Pangea moved north and south, which it did substantially, the core elements moved off-center to conserve angular momentum. This is the “balance” he refers to.
If interested see http://www.dinoextinct.com/page13.pdf
Dinosaurs existed. A huge group species of them even. They ruled the earth for million of years but eventually became extinct. What you are asking for is a new species, as huge as a dinosaur, just popping into existence? That’s not how evolution works. Also, the earth climate was radically different back then and changed numerous times too. All in all there have been, i believe, 5 big mass extinctions on earth, wiping out as much as over 90% of species each time.
Yes, it *is* how evolution works. Increasing size is one of the easiest changes to select on. This is how you get island dwarfism and gigantism on such small time-scales. How many generations did it take to develop the dog breeds chihuahuas and St Bernards? Selection happens faster the bigger the fitness advantage; if there were major advantages to being a giant enormous dinosaur-sized creature, the niche would be filled within a million years, easily.
> People are fascinated by the giant creatures that used to live on the earth. Intuitively, because we don’t see giant animals in the world around us, there’s a natural tendency to ask “Why?”. And being the pattern-seekers that we are, we intuitively believe that there must be a reason why the animals back then were huge, but the animals today aren’t. It can’t just be random chance. So people keep coming up with reasons.
> … trying to explain something that doesn’t need explaining, if only they’d bother to do the damned math, and see that all it takes is a relatively small anatomical change.
You didn’t really explain why either, you’ve just explained how their muscles would work. I’d be interested to hear why the ecosystems of the dinosaurs tended to support larger animals.
Hasn’t José Canseco ever seen the movie Jurassic Park? Those dinosaurs had no trouble walking in current gravity. Q.E.D.
Oh man, Canseco was the guy that started all the fuss about steroid use in baseball. No one believed him then either, until we started to see more evidence. Gravity, I’m keeping an eye on you!
It’s strange that Canseco would tweet this. I had recently watched a video of a mathematical physicist speculating about life on other planets and the restrictions gravity would play.
See the 39:48 mark.
I also recall reading that land animals on Earth probably didn’t exceed 120 metric tons.
I don’t disagree with any of your conclusions, but I do have to take exception with one of your statements: “First, the earths core isn’t some lump of stuff that can putter around. The earth is a solid ball of material. It’s not like a ball of powdered chalk with a solid lump of uranium at the center. The core can’t move.” I think the best evidence that we have is that the core of the earth is actually liquid, and certainly the mantle is at least semi-fluid. That said, you were absolutely correct that the center of mass wouldn’t change, and certainly wouldn’t cause a noticeable change in gravity.
Michael:
If memory & the “Fount of All Knowledge” serve, the core of the Earth has both a solid iron-nickel component (inner core) and a liquid component (outer core).
There’s another problem. As Tim G mentions, animals didn’t weigh 200 tons. My understanding is that originally, they thought that dinosaurs did weigh this much but more recently the weight estimation has been revised downward significantly. In fact, I think they now believe that the heaviest dinosaurs on land only weighed 20 tons at most.
If a palaeontologist could weigh in (excuse the pun) I would be grateful.
My vote for the ‘humans hunting’ theory. Everywhere humans have appeared, large animals have perished.
As I understand it (but I’m too lazy to do the math), the combined mass of all continents, with all the mountains on them, is almost negligible compared to the mass of the mantle and the core.
Also, the core would have to move away from the center of the Earth A LOT to cut the surface gravity by, say, 10%. GMm/R2 and all that. This would have caused a colossal wobble in the Earth rotation.
For surface gravity to be actually lower by 10%, the pangea supercontinent would almost have to be in orbit far above average sea level.
Remember, gravity is _imperceptibly_ lower on top of Mount Everest, 9 Km up.
I ought to try my hand at the math, bummer.
Shannon, if all the continents lumped together on one side of the Earth were so heavy to the point of changing the center of mass of the Earth, it would “move” *towards* the new mass concentration. Presumably, the Earth core would follow. The critters walking on the –presumably heavy– continents would be heavier, not lighter.
I’m trying to picture a mental model of the Earth with a single big continent, 2 Km thick, made of pure osmium. Despite stacking the deck that way, it doesn’t help lower the local gravity at the surface. No way, Jose!
Very interesting stuff. One observation: I just wish you hadn’t called Canseco a “dumbass”. No matter how ridiculous a person’s claims are, please don’t sink to the low level of name calling. You are a better person than that.
On a more positive note, I discovered your blog through your very insightful comments on another forum, and found some excellent reading. Thanks for writing.
Kind regards,
Fred
OK, I’ve done the computations.
F=GMm/r2
Here G is the gravitational constant 6.674×10^-11 Newtons
M is the mass of the Earth, 5.97×10^24 Kg
m is our test mass of 1 Kg
r is the distance from the sea level to the center of the Earth, 6,371,000 m
Let’s compute F:
I get 9.81 Newtons as the gravitational force at sea level. So far so good.
Now let’s suppose the dinosaurs were all living on a very, very, very high plateau, a plateau so high that the local gravity force there was 10% lower, around 8.829 Newtons.
Let’s calls this height h.
G and M stay unchanged, let’s compute which (r+h) squared would give 8.829 N.
I get 6717760 for r+h, so h=345760
There you have it. The dinosaurs were all living on a high plateau 346 Km above sea level.
The dinosaurs fossils should exhibit very very good lungs.
As an aside, an obvious problem with Neal Adams’ notion is that if the Earth (along with everything on it) were constantly expanding (that is, increasing in volume), assuming mass stays constant, then the mass of Earth and its contents is getting increasingly more diffuse. If you consider the centre of mass of any given object as being a point mass, then every object on Earth is getting farther and farther away, over time, from every other object, and from the centre of the Earth’s gravity as well.
My high school physics is an increasingly dim memory, but I recall that the farther away masses are from one another, the less gravitational attraction they have towards one another (or, more up-to-date, the less their gravity-imposed distortions on spacetime affect one another).
It follows that gravity would be stronger during the Mesozoic when everything was much smaller (volume-wise) and closer together.
I’m making some simplifying assumptions (treating objects as point masses, in particular) but since it’s to rebut something that is already demonstrably false I hope it’s not too mangled an effort.
Actually, according to Adam’s crazy theory, that’s not a problem.
First: He doesn’t say that the earth is expanding with constant mass. He believes that new matter is constantly being generated in the earth’s core.
Second, he doesn’t believe in gravity. According to his theory, you aren’t really attracted to the earth. THe earth is just constantly pushing up on you as it expands.
Mr. Canseco must have read my theory, ‘The Gravity Theory of Mass Extinction’ which explains how the core elements shifted. The law of conservation of angular momentum cannot be violated. When Pangea moved north and south, which it did substantially, the core elements moved off-center to conserve angular momentum. This is the “balance” he refers to.
If interested see http://www.dinoextinct.com/page13.pdf
“Gravity had to be weaker to make dinosaurs nimble”
This is pure comedy gold.