Left or right handed.

[niko]

Hallo everyone !! I would like to know the opinon of the mamber's of casebook on the following - was jack left handed or right handed ? my personal opinoin is that he was left handed, and don't ask me why !!

Niko

[RivkahChaya]

I have a question on that topic for people who know more about the Victorians in general: how common was it to force a left-handed child to switch hands in school?

My grandfather could write with both hands, and could do some cool parlor tricks, like writing his first name with his left hand, and his last name with his right hand, at the same time. He was a lefty who was switched over in school.

Some people don't have a distinct hand dominance, but very few people actually do everything equally well with either hand. People with mixed dominance usually have certain tasks that they do with one hand, and certain tasks they do with the other hand. There are books on the reasons, but the short part is, while there is actually a gene for right-handedness, there is no gene for left-handedness. About 80% of the European (and I think it's about the same for African) population has the gene. The 20% without have a 50% chance of ending up with one or the other hand as dominant. Back when child were actively pushed to be right-handed, I'm sure it was smaller. Whatever factor determine hand-dominance in people without the gene, though (and no one is really sure what they are), at least some of them happen in utero, since so many left-handers have enormous difficulty switching, when they are asked to switch in school, at the age of five or six.

Moreover, a few left-handers have the gene for right-handedness, but any accident that effects either motor control on the right side, or the right hand or arm itself, at or before birth, result in a child who is left-handed, with seemingly little difficulty, albeit, it's almost impossible to separate difficulty that results from being left-handed, from difficulty that results from the same problem (like a stroke at birth) that necessitated the child becoming left-handed.

The reason I bring this up, is that it is possible, if JTR was made to write right-handed in school, he may have used a knife, and done many other tasks, left-handed, but still used his right-hand for writing, and not therefore been someone other people would identify as "left-handed" when asked. Or, he may have been able to use a knife with either hand. The latter is doubtful, since he seemed particularly skilled with a knife, and using the same hand consistently helps one develop skills faster (and may be the evolutionary advantage of hand-dominance in the first place).

[niko]

obligated right hander !!

Hi RivkahChaya, funny you mention it , I for one was obligated to write with my right hand where I was left handed, today is the day that I write with my right hand but in sport's where a bat is required I use my left hand the same as with a hammer or other tools, all the best.

Niko.

[RivkahChaya]

My husband and son are lefties, but my son still occasionally does things right-handed like it's not a big deal. He's six. It seems you can have another kind of mixed dominance, because you have a dominant eye-- or rather, side of your face. It's usually on the same side as your hand, but it doesn't have to be.

My face it left-side dominant, even though I write and use tools right-handed. I actually knew this, because I was told this be an optometrist years ago, but when I was in the military, they checked us for eye dominance, because people usually fire rifles better according to eye-dominance than hand dominance. Everyone who had different eye/hand dominance was told to try the shot-group (part of setting your rifle site) twice, to see which side was better. It was interesting. About half of the left-handed people ended up as right-handed shooters, and about 10% of the right-handed people (I was one) ended up left-handed shooter. I didn't know about the righty gene then, but now that I do, it makes statistical sense, if you assume that the gene also controls face-dominance, but the chance factors that determine hand-dominance in the non-right-gene people are independent of the factors that determine face-dominance.

BTW: speaking of statistics, because of the gene, out of a group of identical twins, you will have more that are a right-handed/left-handed pair, than you will have pairs that are both right-handed. (The majority will still be right-handed/right-handed, though.) It's counter-intuitive, but it's the phenomenon that first put people on track of a gene for right-hand dominance. Which is, BTW, a dominant gene. I don't know if there's any discernible difference between people with one copy of it vs. people with two copies of it. I also don't know if people with the mixed hand-face dominance don't have the gene, but I think there's a good chance, because there are lots of left-handed people on both sides of my family, so there's a good chance I don't have the gene.

[Michael W Richards]

Hi there,

Well according to the physical evidence the medical experts concluded that Polly, Annie and I believe Kate were almost certainly cut by someone right handed, ...I dont recall the verdict on the Stride case being as clear,...but there is opinion that the man that killed Mary Kelly used his left hand.

There is support for that last conjecture within the known evidence.

Best regards

[Damaso Marte]

As neutrally as possible, I believe the situation with Mary Kelly is that one of three things is true:

(1) The killer was right-handed, and moved the body to the other side of the bed after mutilating it
(2) The killer was right-handed, and mutilated the body from an awkward position
(3) The killer was left-handed

[RivkahChaya]

I'm asking purely out of ignorance, not because I doubt anyone's conclusions: what is it about a wound that makes it look left- or right-handed?

How would a medical examiner differentiate, for example, between a wound made by backing someone against a wall, and attacking right to left, with the blade coming out of the hand at the bottom, which is to say, with the thumb at the far end; and someone standing behind the victim attacking left to right, with the knife the other way, with the thumb nearest the blade?

In those cases, "left to right," or "right to left" is from the killer's perspective, but from the victim's perspective, it's the same thing. I wouldn't think the angle of the blade would make a difference, since that would depend mostly on the killer's height: the same killer might cut at a more acute angle from behind, but since we don't know the killer's height, we can't really say that a relatively acute angle means a cut from behind, or just a tall killer and a short victim (standing; all bets are off if she was already lying down).

Also, RE: MJK. Do we know whether the killer moved the bed around? we seem to be assuming that he left it in place, so that he never was standing by her right side as she lay down, but he could have pulled the bed away from the wall, and pushed it back. Is there any comment on this in the police report?

Heck, since one picture appears to be from between the bed and the wall, maybe that's the position the bed was in when she was found, and the second photo was after the police pushed the bed back against the wall, for better light from the door. Is any of that recorded anywhere? I don't remember reading remarks regarding anything like that one way or another, but maybe someone has seen something I haven't.

[Michael W Richards]

I'm asking purely out of ignorance, not because I doubt anyone's conclusions: what is it about a wound that makes it look left- or right-handed?

How would a medical examiner differentiate, for example, between a wound made by backing someone against a wall, and attacking right to left, with the blade coming out of the hand at the bottom, which is to say, with the thumb at the far end; and someone standing behind the victim attacking left to right, with the knife the other way, with the thumb nearest the blade?

In those cases, "left to right," or "right to left" is from the killer's perspective, but from the victim's perspective, it's the same thing. I wouldn't think the angle of the blade would make a difference, since that would depend mostly on the killer's height: the same killer might cut at a more acute angle from behind, but since we don't know the killer's height, we can't really say that a relatively acute angle means a cut from behind, or just a tall killer and a short victim (standing; all bets are off if she was already lying down).

Also, RE: MJK. Do we know whether the killer moved the bed around? we seem to be assuming that he left it in place, so that he never was standing by her right side as she lay down, but he could have pulled the bed away from the wall, and pushed it back. Is there any comment on this in the police report?

Heck, since one picture appears to be from between the bed and the wall, maybe that's the position the bed was in when she was found, and the second photo was after the police pushed the bed back against the wall, for better light from the door. Is any of that recorded anywhere? I don't remember reading remarks regarding anything like that one way or another, but maybe someone has seen something I haven't.

Hi Rivkah,

The angle of the blade, or the appearance of direction can be easily addressed by the physical manipulations required to perform some of the acts. The man was left handed, based on the physicality and the physical evidence.

We dont know whether the killer moved the bed, only that he moved Mary...so Im wondering why he would bother with the bed if he could just move the corpse instead? He centered her on the bed, meaning, he had enough room and access from where he was...now, was that on the partition side, or the left side? The Police of course insisted that they left everything untouched, so we have to assume that the shot taken from the right hand side of the bed across Marys empty midsection was taken using a remote shutter camera that was placed on the bedding stuffed between the wall and bed. Check the angles for yourself. Whether they put the bedding there for that shot isnt clear.

The placement of the materials on the night table, presuming that we have someone standing on the only side of the bed that he could, the left hand side, dictates that a left handed man almost certainly was the case here.

Try and reproduce those actions using both left and right hands as the primary...see which one works more efficiently and easily. And you can forget the one ambidextrous Jack idea...1% or less of any given population is technically ambi...so its 99-1 against that idea.

Cheers Rivkah

[The Good Michael]

Kelly is debatable, but the other victims seem to be done by a righty to me. Of course if the killer made them lose consciousness first, I suppose he could have used either hand as needed.

Mike

[c.d.]

I have always assumed that a qualified individual could make that determination with a fairly high degree of accuracy. But I still think that we need to take these medical reports with a grain of salt. I have no doubt that these doctors were qualified and had certainly seen their share of knife cuts. On the other hand, I don't think that they were pressed really hard at the inquests. We don't know how much time was spent on their examination or all of the factors that they took into account or failed to take into account.

c.d.

[c.d.]

You lost me on this one, Michael. I am looking at the photo from the perspective of the foot of the bed. I see the table on the right. It seems to me that it would have been a lot easier for her killer to be on the right side of the bed in order to reach the table. If that is the case, he could have done so with either hand.

c.d.

[RivkahChaya]

To make a killing slice at the throat, he could have been sitting on the bed behind her, and then probably could have used either hand.

The angle of the blade, or the appearance of direction can be easily addressed by the physical manipulations required to perform some of the acts. The man was left handed, based on the physicality and the physical evidence.

There's a sort of triad of facts, it seems to me, and if you have two, you can deduce the third. However, I think we have just one. The three things would be 1) where the person was standing (in front or in back); 2) the direction of the wound; and 3) the handedness of the attacker. We know only the direction of the wound.

It's my understanding that early reports of JTR being left-handed came from observing the wound, and assuming the attacker was facing the victim-- or standing over her with feet and head oriented the same as hers (as though to assume the missionary position). Once it occurred to people he might have been behind her, then the deduction that he was left-handed was no longer valid.

If anyone knows more, please correct, me, though.

We dont know whether the killer moved the bed, only that he moved Mary...so Im wondering why he would bother with the bed if he could just move the corpse instead?

Because a right-handed killer, "working" (forgive the expression) on her face could sit on her right side with one or both legs off the bed, if it was pulled out from the wall. Otherwise, he has to kneel, or sit cross-legged.

And you can forget the one ambidextrous Jack idea...1% or less of any given population is technically ambi...so its 99-1 against that idea.

Well, whatever the population is, it's not 99:1 against the idea. Ambidexterity (or forced right-handedness) or the killer could contribute all sorts of invisible variables we're not accounting for.

But, we also don't know what percentage of Victorians could effectively use both hands. The reason for my long-winded post about handedness, genetics, and forcing children to use the right hand was to point out that whatever hand JTR used for the knife was probably consistent, even if it wasn't the hand he wrote with. If we define ambidextrous people only as those who can do all tasks more or less equally well with both hands, then the number is far below 1% or the population. However, mixed dominance is more common. I don't know what the percentage is, but I suspect that whatever it is now, it was higher in Victorian times, due to children being required to write only with the right hand. I don't know if that was true, though-- that children were required to switch. It was true in the US from about 1910 on, fading from practice beginning around 1970. I don't know if it was something new, in the 20th century, though. Or if it happened in the UK as well as the US.

I wouldn't, let me emphasize, expect a mixed-dominance JTR to sometimes kill with one hand, and sometimes with the other. However, he could be someone who used a knife left-handed, and wrote right-handed, so that people who knew him did not think of him as left-handed.

[Nic1950]

Hi

Tricky one! All I know is that I'm right handed and if I was stood at the foot of a bed, I would need to go to the left of the bed and stand or kneel over the body to carry out . The thing is the post mortems were carried out to the best of their knowledge which unfortunately was limited back then. It would be easier if we had a 3d image of MJK and all injuries??

[Mrs. Fiddymont]

It's my opinion that Jack was right-handed. After all, the vast majority of the population is. And I agree that the doctors who first suggested he may have been left-handed seemed to assume he attacked his victims from the front--I think it's much likelier he struck from behind, which increases the likelihood that he was using his right hand.

My uncle was left-handed (he was born around 1920, in the US) and he had a rough time in school because his teachers insisted that he write with his right hand. I think all schools in the US did the same at that time--why they so objected to lefties is beyond me! As I recall he still preferred his left hand into adulthood, and I don't blame him. I'm right-handed, and I could never master writing (or doing anything else!) with my left hand.

I think left-handedness is more common in males (not certain about that) but I had a female friend in school who was left-handed. We started first grade around 1961 (yeah, I'm old lol) and I don't recall teachers ever trying to force her to use her right hand. Our classrooms always had one or two specially made seats for left-handed kids, so being a lefty by then was not discouraged at all. And I can tell you, my left-handed friend has far better handwriting than mine!!

[RivkahChaya]

I think left-handedness is more common in males (not certain about that) but I had a female friend in school who was left-handed.

It's more common in people with learning disabilities, although, you have to read that carefully, because the majority of people with LDs are still right-handed.

I read a research paper on this once, that note that lefties who wrote with a hook tended to have learning or perceptual problems, while those who wrote holding the pen in a mirror image of the way a righty does, and no greater instances of any other problems. I asked someone who was doing some research into handedness and autism about this if it was possible that people who wrote with a hook were genetic right-handers who used their left hand as a result of some very minor trauma or damage to their left hemisphere, and if that could account for LDs as well. She said that was a good theory, although she didn't know about any research.

I know the documentation of lefties and higher incidence of learning disabilities caused some well-meaning teachers, who failed at cause & effect, to make left-handed children use their right hands, in order to prevent learning disabilities.

Since boys have a higher incidence of learning disabilities, that may account for the perception, although maybe men who are lefties, have a higher incidence of "hooked" writing, so you tend to notice that they are left-handed.