What Are the Odds?
Tracing Lincoln's Carbon

Jim Hartline
University of Oklahoma student
jhartline@ou.edu

[Editor's note: The following came as an email to my husband, Dr. Doug Gaffin, from Jim Hartline, an OU student who had taken his Introductory Zoology class. Doug forwarded it to me, thinking I might want to use it in Labstracts as an example of a thought problem that integrates many aspects of chemistry and biology. I asked for, and received, Jim's permission to include it here.]

Dr. Gaffin:

As you may remember, you once asked for anyone in your Zoology class who was so inclined to figure out the odds that anyone had a carbon atom from Abraham Lincoln in them.

Well, I was hauling dead branches today, thinking about them a bit, and before I knew it I started thinking of what you said. When I got done, I HAD to figure it out. So I did. Sort of. Here goes:

Abraham Lincoln wrote that he weighed "on average 180 pounds," or about 81.6 kg. The human body is about 18% carbon by weight, so he likely had about 11.424 kg of carbon in him when he died. This is where all seriousness ends.

Now, assume that when he died his body was atomized, instead of buried. Furthermore, assume that every single carbon atom from Lincoln spread evenly throughout the atmosphere. Furthermore, assume that not a single atom of carbon from Lincoln can be absorbed by anything except for a living human being, and also assume that only the human beings presently alive could absorb one of Lincoln's carbon atoms.

Now, the atmosphere weighs roughly 5.1 x 10^18 kg, according to Wikipedia. Also according to Wikipedia, the atmosphere is about .05333% carbon by weight, if you add CO2 and CH4. So, there is roughly 2.77 x 10^15 kg of carbon in the atmosphere.

That means that if Lincoln's body was atomized (etc. etc.) then the carbon in the atmosphere is 4.1 x 10^ -15% comes from the body formerly known as Lincoln.

Now, at present time, according to the US Census, there are roughly 6.448 x 10^10 people living in the world today. Furthermore, each of these people weighs, on average, about 70 kg. Assume that all of the carbon in their bodies is absorbed from the atmosphere. That means that each person absorbs roughly 12.6 kg of carbon, or 4.5 x 10 ^ -15 % of the carbon in the atmosphere. If 4.1 x 10^ -15% of the atmosphere's carbon was Lincoln's, that means that, statistically, each person will absorb roughly 1.9 x 10^ -29 kg of Lincoln. But...

That means each person absorbs roughly .000011 atoms of Lincoln's carbon atoms. That's impossible, unless of course Lincoln was first used as fuel for a nuclear reaction before he was atomized.

If everything goes as assumed, then, on average, roughly 1 in 9,000 people have a single Lincoln carbon in them. If our class had roughly 500 people in it, then, if everyone showed up (yes, I'm still in my fantasy world) there would be a 5.6% chance that someone in your class had a carbon atom from Lincoln in them. Teach about 20 classes, and you've got it!

But.

That assumes that no carbon gets absorbed anywhere else by anything else. That the entire atmosphere gets absorbed at some point in time by a human. That every single carbon atom in Lincoln was released into the atmosphere.

President Lincoln was buried at Oak Ridge Cemetery in Springfield, Missouri. He was buried inside of a 177-ft. tall granite tomb. So, not a lot of his carbon probably managed to escape. Something else further complicates the matter, however.

So many people tried to steal Lincoln's body and hold it for ransom that Lincoln's son Robert had his body exhumed and reburied within several feet of concrete in 1901. Pretty foolproof. So no carbon for our class.