Many culture have believed in reincarnation. In the East India, China: probably under Indian Influence and Tibet. In the West some Ancient Greeks embraced the idea, The Celts tended to believe in reincarnation with examples in some of their myths, as did the Vikings who believed one would be reincarnated in the same family. I read that early Christianity included a belief in reincarnation, and a verse in the Gospel of John can be read as supporting the reincarnation hypothesis. The value of this evidence can be put into perspective by looking at the medieval belief the world was flat, and the Satanic Ritual Abuse Panic of the late 1980s which recycled anti Jewish myths and atrocity tales originally directed against Christians.
There is some evidence suggestive of reincarnation, mostly from India (assessed by Stevenson) where belief is strongest and evidence most likely to be corrupted by wishful thinking. Evidence from hypnotic regression must be treated with extreme caution, especially when dealing with a reincarnated Cleopatra: it seems unlikely any regression will ever turn up Hitler, Stalin or Pol Pot but such a case would be at first glance merit investigation
I recall reading that group of researchers into the spirit world asked a guiding spirit about this and were told reincarnation happens but is uncommon.
And as always I want to know why? If even one person is reincarnated even once that is a paradigm shaking event. The reason why could be a second.
There are two main schools of thought about the purpose of reincarnation. One school says it is to let us learn and the other says it is to repay “Karmic Debts”.
Imagine your child fail their school exams one year. So you send them back to do the year again. But first you block their memories of that year. But just before you block the memories you say
“I want you to do better this time, if not you will keep going back till you succeed” . Imagine what any child care official or Director of Education would say if you proposed that as a way to educate your child. You would be in prison faster than you can say “care order”. Believers note that spirits tell them remembering past lives would hinder progress in this one. Believe that as you will.
Imagine someone commits a crime. You send them to prison and say “ If you do it again you go back to jail: then block their memories of the crime. Not an effective way of giving feedback. In any case most if not all injustices can be settled with an apology and a drink in the Afterlife
“Sorry I had you castrated and sent to the mines, let me buy you a double whiskey”
“OK, I can laugh about it now, make it a treble”
Of course the education hypothesis may be true, in which case reincarnated souls may be smarter, not necessarily academically: A successful gangster is never stupid, even though they cannot tell you the cube root of 79 ( not even to four and bit), and politicians are very clever, at least at looking after themselves, in a world devoid even of the ethics a gangster needs to survive (skimming the take on a protection racket or sleeping with another gangster's woman tends to result in death: in politics, skilfully done it can result in promotion). If you doubt this note that they tend to retire on full salary.
The Education Hypothesis is thus basically flawed, which means either no one is reincarnated or everyone is or some people are reincarnated. But the reason why remains unclear. Perhaps we are just here to amuse a bored god or set of gods. In which case the least we can do is be amusing no solemn.
Either nobody is reincarnated, some people are reincarnated, or everyone is reincarnated. The first , given the increase in human population since prehistoric times, suggests a continuous creation of souls to inhabit bodies or that the body is an incubator in which souls develop. For most of human history the time spent in a body was short: up to the 19th century few lived more than 12 months and if nobody is reincarnated there would be lot of undeveloped souls in the afterlife.
The last possibility suggests our consciousness (spirit) needs a body, possibly to be able to experience more keenly, possibly because it cannot survive long without a body: how long can a bodiless spirit survive and why does it need a body. It also indicates that somewhere is a reincarnated Buddha and a reincarnated Jesus (Now who else can I offend?).
In The Journal of the Society for Scientific Exploration Vol. 14, No. 3, pp. 411–420, 2000, Bishai contrasts the linear model in which no soul reincarnates with a cyclic model in which each soul spends some time in an afterlife and then reincarnates and shows that the time in the afterlife shortens, as the population grows, from 57,000 years in 50,000 BC to about 106 years in 2000AD assuming a total stock of 10 Billion souls, and from 571,400 years to 712 years for a stock of 100 Billion souls. This may explain why infant mortality was high for so long: new bodies were needed for short term tenancies and had to be vacated because resources like food were scarce, Every infant that died could spend time in the after life and be sure of a body in time to survive.
If as some cultures think, one can be reincarnated as an animal, the pressure would be reduced further. It is of course unclear in this model whether the human state was regarded as superior or inferior, though population growth might suggest the former.
The middle hypothesis, that some people reincarnate, is the most intriguing of all. Why would people reincarnate given a choice? One British academic said he hoped reincarnation was false since having drawn an eel from a barrel of snakes he was unwilling to put his hand in the barrel again. Perhaps those who reincarnate have a mission to fulfil, or are just masochistic.
No one knows for sure if Reincarnation occurs. If it does no one knows why. If it occurs no one knows how it is decided who reincarnates and as what. That is a whole load of ignorance to investigate. And if it turns out reincarnation is impossible the question of what produced the evidence we have becomes important in the study of mass deception.
Right now I favour the idea that life on earth is a tourist trip with a lot of dodgy operators who put you up in a resort with half finished hotels and salmonella ridden food, with some offering misery trips, like a survival holiday or the theme camp in Eastern Europe that recreated the experience of a concentration camp. Add in a few secret agents on a mission, some independent travellers and a few misfits in the after life and the world begins to look like fun instead of all the grimly serious puritanism the religions of the book ( and others) try to foist on us.
I remain convinced however that all the theories above may be partly or wholly wrong. The world is never that simple.