Reptile & Amphibian Forums

I have often wondered about a genetic predisposition for aggression/tameness in reptiles. I understand some people do not like the idea of discussing mammal behavior and anatomy along side that of reptiles or other ectotherms. But I feel the argument that they may be more closely linked than previously thought is an interesting one.
Considering a few of the remarks made in the thread below, along with other remarks I have read over the years and personal observance, I feel there may be fresh evidence for (at least some) of this argument.

The quotes in question are:

Randy Remington:

"However, half of his daughters with a normal (i.e. non-aggressive) ball where a little nippier than normal and more likely to hiss (especially for the first year or two) and so where half of his grandchildren with one of the aggressive daughters."
He continues,"...I'm sure past experiences (or lack of them) do play a part in a ball python's temperament but I think there is probably also a genetic component."

Lord Dreyfus:

"I think it is obvious that temperament is genetically linked. Its been proven again and again with domestic animals. Even with snakes you can see a difference if you look closely. You import a bunch of wc snakes and the ones that adjust live to breed. The ones that are too high strung die. Retics had a terrible reputation for years...now they are mellowing out. Compare a wc baby burmese...or even hatch one out of the egg yourself to one that has been cb for 4 generations or more. They may not be "tame" animals...but they don't spook as easily, and are not as defensive.

I raise my own feeder mice and rats and I've taken pinky mice out of wild nest I've found in my buildings and mixed them in with the baby mice I had. Both wild and tame were raised up by the same mother and had the exact same treatment from me. You could never confuse the two. The wild babies never ever tamed down like the others. Ever. The second generation was still more jumpy than the pure cb. Much better resistance to disease and cancer, but were much harder to handle."

Forgive me, if I took your quotes out of context. My point is that aggressive tendencies as experienced by these two gentlemen seem to be genetic.
In my own experiences, this has also been the case. The calmer the parental lineage the more likely the resulting offspring appear to be. Not only this trait, but also a stronger and more consistent feeding response as well. Of my collection that are purely CB (both parents were CB) I selected only animals that were calm and considered "garbage dumps" by their breeders...meaning anything thrown their way would invariably be consumed within a short time. Their resulting offspring all appear to have this strong feeding response and demeanor.
On the other hand, those balls in my collection which are WC or only one generation removed from the wild AND display aggression have all had clutches where all or very nearly all of the babies were much more reluctant to feed and/or displayed similar levels of aggression.
I have a theory that if bred for tameness alone, not only would we see a drop in aggression, and an increase in "proper" (healthy?) feeding response - meaning less picky eaters and a more consistent feeding schedule, but also a more diverse display of color and pattern morphs.

I know that last statement would/could brand me for life in some circles and have me permanently barred from others, but bear with me for at least a little longer. I am open to debate as I feel this is a subject that has not been proven one way or another or entirely explored due to the constant importation of WC morphs, which would muddle the waters of this experiment.

First off, considering the domestication of Canis familiaris from Canis lupus - the common dog from the wolf - scientists pondered how such genetic diversity could result between the two and between all of the "morphs" of domestic dog we have today. In Novosibirsk, Siberia an experiment 40 years in the making has taken a species very close to C. familiaris which had never been domesticated - Vulpes vulpes (the silver fox) and selectively bred these animals for ONE TRAIT ONLY - tameness.
The experiment is the brainchild of Soviet scientist Dmitry K. Belyaev. Initially, he set out to breed a tame fox. This particular fox was already being bred for it's fur, but remained fairly aggressive and skittish with humans. A tame fox would be very valuable for these breeders for obvious reasons.
Through selective breeding of only the most tame animals and constant removal of those individuals who displayed the most "wild" tendencies from the breeding pool, he eventually stumbled upon something remarkable. By the sixth generation, the foxes being born had physical characteristics found only in previously domesticated animals such as floppy ears (only the elephant has floppy ears in its wild state), skulls that are unusually broad for their length, variations in coat length, curly hair. The animals were also friendlier to humans and appeared dependent upon them. In fact, of those that occasionally escaped it was these "tame" individuals that would invariably return to the farm.
By the tenth generation something dramatic happened - color and pattern "morphs" began popping up randomly and in a fairly sufficient number to be noticed. Now, for anyone unfamiliar with the silver fox, it is a very plain looking animal and NOWHERE in the wild are variations is color or pattern found. Most of you who have read this far have at least a general level of knowledge concerning genetics and would realize that for a color (or pattern) to "pop up" is almost entirely unheard of, and never heard of ten generations into a breeding group. (These animals were being inbred, obviously, so I make the previous statement adding one exception: genetic deformities resulting in an obviously deformed or sterile creature.)
So what was happening? In essence, Belyaev was breeding animals with the lowest adrenaline response (less adrenaline = less likely to exhibit a "fight or flight" response). It turns out that the genes responsible for determining the foxes color, pattern, and physical makeup run along the same paths as those that determine the animal's behavior and adrenal response. When breeding for a certain behavioral and biochemical profile they were also inadvertently changing the master genes that control physical development.

These foxes went through the very same changes in physical makeup, as did the wolf when it became our "best friend". Is it not possible that we as breeders of ball pythons are domesticating these animals and are possibly creating (or could possibly create) some of our new morphs?
I'm interested in the yellow belly/leucistic equation, it seems these animals were always in our collection and now out of the blue there is this assumption that they create leucistic animals. How tame are the resulting offspring? How about feeding response?
Also, I've heard that Spider balls are very tame (by comparison to other morphs) and have excellent feeding responses.
What about some of the other morphs we are seeing in the hobby/trade? Has anyone noticed that certain morphs/combos are tamer than others in their stock? I'm interested in hearing from breeders who have a fairly large breeding stock consisting mostly of purely CB animals.

I have been interested in this for some time now and I'm curious as to what others may think. I understand that I most likely made some errors in some of the information above. Please forgive me, it is about 4:00 a.m. and I am writing this off the top of my head. Please do a Google search on this topic and decide for yourself from a source more reliable than my memory.

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In the right hands patience, curiousity and willingness to learn can work miracles. In the wrong hands they are mankind's curse and nature's greatest fear.

You tend to get what you select for and tend to loose ground on everything else.

I saw something about those foxes also. It was pointed out that the multi colored fur made them useless for the original purpose of the experiment, the fur trade. Once they exerted all their selection pressure on temperament they lost ground on fur quality.

With morphs we tend to exert most of our selection pressure on showing the morphs. With an expensive morph even ill tempered and poor feeding animals are bred. When we exert lots of selection pressure on appearance we should expect temperament and other qualities to tend to suffer. Something we will have to stay on guard against.

I've long heard the idea that aggressive snakes will tend to be better feeders and even breeders. Some have pointed out that the more fearful animals might actually tend not to feed well. Maybe the original premise that aggression = good feeding response is completely inaccurate or maybe only for certain types of aggression. Maybe aggressive animals weren't purposely bred into some morph lines and the perception that some morphs tend to be more aggressive than average is either false or accidental due to not selecting against it. I know someone who just got an albino hatchling and reports that it is both aggressive and a good feeder. I've heard of several aggressive axanthics. Of course maybe most people don't bother to talk about aggressive normals (I've got one, pretty good feeder too).

Another interesting thing about selection happens when you select against something. I've heard an interesting story about red Holstein cattle. The red gene is recessive and undesirable because a Holstein is "supposed to be black and white". For aesthetic reasons it was selected strongly against. The only way you kept a proven het for red cow was if she was such a good producer that you couldn't stand to get rid of her. The story goes that a geneticist recognized this and founded a heard of red and white Holsteins that was superior to the black and white ones at the time due to the fact that the red gene had been selected against for some time.

Maybe if we start working hard at selecting against aggressive ball pythons then the only aggressive ones left will be the ones that are such good eaters that we can't stand not to keep them as breeders. Could be a lot of work to keep the ball python morphs stereotypically nice tempered.

well my albino male is agressive and he isn't a very good eater. He eats randomly and not what or how much he should eat.

I am really intrigued by some of the points you have brought up. The idea that the color varieties only appeared after people began selective breeding is very interesting, and pertinent to what we are seeing in ball pythons. I would be curious if the color varieties had once appeared in the wild, but due to natural selection, they did not survive. With the balls, we see some of the morphs being imported. So we know some of the patterns/colors would still be present in the wild.

In humans we know that to a certain extend personality traits are passed on genetically. (We know this due to identical twin studies in which the twins were raised apart) Why wouldn't that be considered true for reptiles as well?