According to the Tibetan Book of the Dead it can take anywhere from a split second to 49 days to be reborn, on average. Some people will remain in the bardo for very long periods of time, centuries... The TBD does not posit a soul.
According to Tibetan lore, the mind waiting to be reborn sees one's future parents copulating and hovers over them, and while feeling attraction to one and aversion to the other is born the sex opposite the attractive one. This event happens at conception, not 49 days after conception.
Rene Descartes is not an authority on the function of the pineal gland. The pineal gland is not the seat of the soul. If there is a soul, it is dependent on the whole organism not one organ or one gland inside one organ.
Modern science makes it clear that both this account of rebirth and Decartes mind/body dualism is unfounded. Spiritual practice, IMO, should be excised from folklore and dead theories from the past.
HH the Dalai Lama has even said that one of the fundamental treatises of traditional Buddhism, the Abhidharma should be abandoned, because modern science is refuted it totally. Our spiritual beliefs must stand scrutiny or be abandoned.
There is evidence of people remembering lives previous to their own. Does this mean that that person experienced that past life? That depends on if the person recalls those memories in the first person. But even if one experiences a memory in the first person, couldn't this be similar to watching a movie in the first person? It is just a point of view. This begs the question, What is it that accords ownership to our memories or to anything?
Who we are constantly changes. Our mind and personality is like a rushing river. It is never the same. Suppose I reproduce a ship called the Nausea, as follows: Every few months I remove one plank, and replace it with a new plank. The old plank I keep in a safe place. After some time, all the planks of the Nausea are in a pile, and I can rebuild the original Nausea. Now there are two Nausea ships? Or is there? In the meantime, all the tasks and events schedule for the Nausea are endured by the ship with all new planks.
Who one was in the past life is not the same person as is born. Close but not same. It is only close enough for the karmic repercussions of the past to rebalance.
My own limited first-hand experience comes from meditation and a few trips. Waking up in another body entails being someone else. But that first-person(ness) is not different than my own. Philosophers of mind are big on making it seem as if there is unique quality to each persons sense of self. This is just an erroneous intuition.
Perhaps there is some special aroma to our mass of memories and our experience of our own body-mind this moment. But would it smell the same if "someone else" where in that body? I believe it would.
We like to talk as if there is something unique about ourselves, but this is just a useful way to go about talking. I'm positing an utterly common nature, hence, common sense, to the sense of self, to our first-person-sense. For those like us delving deeply, this should not be missed.
Reincarnation is misunderstood, oversimplified. All the traits contained in the personalities are like a list of possibilities. As we go through life we pick up traits and drop others. Some newborn may have substantially all the traits of someone who died, but not all. The purpose of positing rebirth is to make sense of karma, which is a notion of justice, retributive effects of one's own actions. Karma give one a sense that one's acts will not die with you. You will be reborn and reap the punishment or reward.
This is a very simplified rendition of the facts. Reincarnation is not well understood. When a new person is born with all the proclivities (desires/aversions) substantially similar to one who has died, those potential desires/aversions magnetically attract the unborn effects of previous acts.
Thus, we can just as easily understand that our act effects the newborn that we will become, or just that our acts reverberate into the future broadly.
I have a sense of experiencing past lives myself. What do we make of unlearned skills, like children born violinists, athletes or fighters? In esoteric yoga, there is the mention of an indestructible wind which is carried from death to birth. It is this wind which is tracked by past karma. It is also this wind, also called these seed, which is purified into enlightenment.
The bottom line is we are all inter-dependent, and an inter-being. We bear the effects of our own past acts and the effects of others. We shoulder each other crosses. All of existence is of one taste; there is no difference between us. Equality runs through and through.
