Enjoy fast, free delivery, exclusive deals, and award-winning movies & TV shows with Prime
Try Prime and start saving today with fast, free delivery

Kindle
$17.40

Available instantly

Hardcover
$39.99

Paperback
$31.99

$31.99

Get Fast, Free Shipping with Amazon Prime

FREE delivery Thursday, June 20 on orders shipped by Amazon over $35

Or fastest delivery Wednesday, June 19. Order within 19 hrs

Arrives after Father's Day. Need a gift sooner? Send an Amazon Gift Card instantly by email or text message.

Select delivery location

In Stock

$$31.99 () Includes selected options. Includes initial monthly payment and selected options. Details

Ships from

Amazon.com

Ships from

Amazon.com

Sold by

Amazon.com

Sold by

Amazon.com

Returns

Eligible for Return, Refund or Replacement within 30 days of receipt

Returns

Eligible for Return, Refund or Replacement within 30 days of receipt

This item can be returned in its original condition for a full refund or replacement within 30 days of receipt.

Read full return policy

Payment

Secure transaction

Payment

Secure transaction

We work hard to protect your security and privacy. Our payment security system encrypts your information during transmission. We don’t share your credit card details with third-party sellers, and we don’t sell your information to others. Learn more

Details

Add a gift receipt for easy returns

Other sellers on Amazon

New (2) from $31.99 FREE Shipping on orders over $35.00 shipped by Amazon.

Image Unavailable

Image not available for
Color:

To view this video download Flash Player

Follow the author

Susan Crockford

Follow

Polar Bear Evolution: A Model for How New Species Arise Paperback – June 6, 2023

by Susan J. Crockford (Author)

4.4 4 ratings

See all formats and editions

Sorry, there was a problem loading this page. Try again.

{"desktop_buybox_group_1":[{"displayPrice":"$31.99","priceAmount":31.99,"currencySymbol":"$","integerValue":"31","decimalSeparator":".","fractionalValue":"99","symbolPosition":"left","hasSpace":false,"showFractionalPartIfEmpty":true,"offerListingId":"ahOPu0p%2Fot52x0r3crmh1G36AS%2BAiBc5Ct0jitpj03PfvjfDRuU00LAbhF%2BHCxeJbBrNAuIyUpVkcyTr4%2FDpWHcW1H28aII9MhmJgKVM%2B%2BYraKEGhh%2BeB%2BprHXblqA2MKtdVPZPxigriZG2kbTPkvg%3D%3D","locale":"en-US","buyingOptionType":"NEW","aapiBuyingOptionIndex":0}]}

Purchase options and add-ons

This fascinating story finally brings together everything that scientists have learned about the origin of polar bears, in clear language that non-scientists will understand: not just when and where the species arose, but exactly how it happened and why the bears were able to survive repeated cycles of sea ice change, some of unimaginable magnitude. The book includes a detailed account of the fossil evidence, recent hybridization events between brown bears and polar bears, and summaries of more than a dozen genetic studies that have been done on these bears to determine the most plausible time and place for the origin of polar bears.

For the first time, a biological mechanism explains how this rapid transformation from a brown bear ancestor could have happened. Thyroid hormone, essential for countless coordinated body functions including stress responses, the growth of embryos, and the activation of critical genes, seems to have played a vital role in the vast majority of all speciation events. A testable theory based on thyroid hormone not only explains how polar bears came to be but does the same for domestic dogs, flightless birds like the dodo, and extinct dwarf species like Homo floresiensis aka “The Hobbit” from Flores Island, Indonesia.

If you’ve ever wondered whether polar bears could have arisen more than once or if hybridization with brown bears really did play a significant part in polar bear evolution, this book is for you. It also explains how polar bear biology and behavior have been fine-tuned by natural selection, adapting the species to the highly dynamic Arctic environment of the late Pleistocene, which included interglacial times when sea ice was scarcer than it is today. This book is more than the complete story of polar bear origins: it’s a big-picture account of how evolution works for most organisms. It’s a fascinating story that deserves to be a staple in your home library.