Commenter pumpkinhead is the second person to doubt my claim that brain weight increases by 9% after death so I thought it would be useful to devote a whole article to this. The skepticism is understandable since there’s no obvious mechanism by which this should happen. If I were a theist I might say that when we die we join the spirit world and become omniscient like God and it requires extra brain weight to have all this knowledge.
I first learned about the post-mortem increase by reading J.P. Rushton who cited pg 299 of a 1983 article by Jorgen Voigt and Henning Pakkenberg who write:
Appel and Appel [1942a, b] seem to be the first to point out that the brain weight increases post-mortem, mostly during the first 12 h after death, then more slowly,
totalling an average of about 9%. However, experiments with rats [Boyd and Knight,
1963] later showed that the brain weight in these animals does not change very much post-mortem, and the tendency here is to a loss of weight which, in a single experimental group reached a total of 12%. If the results of Appel and Appel [1942a, b] are accepted our brain-weight results should be approximately 9% above the weight in vivo, as the autopsies are always carried out considerably later than 12 h after death
In the original 1942 article by FW and EM Appel they discuss their equation for predicting brain weight as a function of time since death:
Brain weight (in grams) = 1242.44 + .33 H + 39.72 log H
Here H is the number of hours post mortem.
The curve is certainly suggestive. It suggests that the weight of the brain increases almost continuously after death, at a rate that gradually diminishes. The increase must be limited, but its limit must be beyond the reach of our data. The weight certainly increases for many hours, and possibly it does so for more than 6 days. In the first 12 hours after death the mean weight increases about 47 grams, or nearly 4 percent.
By the end of the second 12-hour period the increase amounts to 63 grams, or more than 5 percent ; by 36 hours it amounts to 74 grams, or nearly 6 percent. If this increase continued for 170 hours after death it would amount to 145 grams, or the amount of the mean loss in weight between ages 25 and 96.
Conjectures as to the implications of this increase are not in order until it has been demonstrated beyond any doubt that the increase is a real phenomenon. Other workers have demonstrated that the weight of the brain varies with the skull dimensions and with the age at death, so there has been no reason to doubt our findings on these points. But no evidence of a post-mortem increase has ever before been presented. It is conceivable that the apparent increase might be due to a chance drift in the age at death, or in the dimensions of the skull, though it is difficult to see why the apparent increase should be essentially continuous and at a gradually diminishing rate if any accident of sampling or distribution is responsible for it. Still, the possibility needs to be investigated
Here’s their data for the brain weight increase, so judge for yourselves how convincing it is.
The Philosopher said:
The only way to really know is to go to the mortuary and measure the peoples brains bruno.
You need the weight before death Philo. A good place to go is a neurosurgery department in a big hospital. Neurosurgeons are great providers of dead body and they know how to handle the dying brain ….
Maybe it’s the polymerization of formal or a similar substance needed to handle the brain. That makes the weight go up.
One should carefully read the protocol they followed to see and they did measure. But that’s beyond my motivation 🙂
The Social Justice Warrior...Returns! said:
If you were a scientist like Pumpkin, you would go to the mortuary and demand to see peoples brains.
The Philosopher said:
Puppys brain is very big to be able to write such good comedy all the time.
The Social Justice Warrior...Returns! said:
Thanks for going through the trouble to include the data that Voigt and Pakkengberg produced however I can’t find the original paper anywhere. At this point I’m curious to find out their methodology. Were the brains removed and weighed straight away and then at various intervals? Were the brains still connected to the veins and arteries at any time during the weighing? Did they use preservatives? Did they assume an in vivo weight and then remove it and weigh it x hours after death?
I still don’t see how the brains could possibly acquire the extra mass(outside of access to bodily fluids or some kind of preservative being used), something seems quite off here.
If I wanted to know how much the brain weighed I would weigh it right after death, end of story. Forgive my ignorance but all this seems nonsensical to me.
Just to be clear, the data’s from:
INTRACRANIAL VARIATION IN THE WEIGHT OF THE HUMAN BRAIN
Author(s): F. W. APPEL and E. M. APPEL
Source: Human Biology, Vol. 14, No. 1 (FEBRUARY, 1942), pp. 48-68
I realize Rushton cited Voight & Pakkenberg, by they in-turn cite Appel & Appel. From page 49 of the 1942 paper by Appel & Appel:
Nothing is known about the conditions under which the organs were
measured, except what Freeman has to say about his own procedures
(1931). Only a fraction of the autopsies were done under Freeman’s
term of office. The post-mortem examinations were done by many
different people, working at different periods in the history of the
Hospital. Nearly 50 years are covered by the records. Brandes (1927)
states that the dura mater weighs 50-60 grams, and that the complete
drainage of the cerebrospinal fluid from the fresh brain may change its
weight by as much as 50 grams. We presume that in all autopsies at
St. Elizabeth’s Hospital the outer meninx was removed from the brain
insofar as it could be, but that the inner meninges, the arachnoid and
pia layers, were not. We presume, too, that the brains were weighed
immediately after removal, and just as they came from the skulls (that
is, without being either rinsed or drained), but we do not know this.
Certainly considerable differences in the weights of brains might result
from different modes of handling.
Seems like one has to assume too much for these measures to be true.
Thanks for the info. Right, well I’m starting to think that given all the variables there is so much that could go wrong. So outside of some reaction with the environment akin to iron oxidation(rust) where the metal actually ends up gaining weight in the long run, I don’t see how there could be any gain in weight. After all the only weight that matters is that right after the brain is removed, so who cares what happens 10 hours later. Surely any gain due to reaction would take much longer than a few hours, perhaps years. But at that point wouldn’t the brain lose weight due to drying up?