"Darwin's World: An Epic of Survival (The Darwin's World Series) by Jack L Knapp

"Darwin's World: An Epic of Survival (The Darwin's World Series) by Jack L Knapp
    https://www.amazon.com/Darwins-World-Epic-Survival/dp/1720070776/
Book number one of a five book science fiction series.  I read the well printed and well bound POD (print on demand) trade paperback that I bought new on Amazon.  I have bought books two and three in the series for reading soon.
In the 25th century, humanity has solved all problems and even created machines for time travel and parallel universe travel.  But, they caused a new problem, humanity is dying out as people have lost the will to live.
So the future scientists are bringing forward dying people from the 20th century, giving them new bodies, and transferring them to a parallel world going through the end of the Pleistocene ice age.  With nothing but a few tools and the clothes on their backs.  Survive or die in the primitive conditions of what will be the southern USA but there are lions, big cats, mammoths, bisons, dire wolves, deer, elk, short face bears, grizzlies, etc.  And chest deep snow in the winters.
My rating:  5 out of 5 stars
Amazon rating:  4.3 out of 5 stars (413 reviews)
Lynn