Summary of Susan Crockford: Failed polar bear narrative; also their origin/evolution | Tom Nelson Pod #187

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In the "Susan Crockford: Failed polar bear narrative; also their origin/evolution | Tom Nelson Pod #187" episode, Susan Crockford, a zoologist, discusses the challenges in accurately estimating polar bear populations and the ongoing debate between Inuit communities and polar bear specialists regarding population sizes. She also shares her theory on the role of thyroid hormones in polar bear evolution and the quick adaptation of species to new environments using the example of the Russian foxes. Crockford also discusses her controversial theory about the origin of polar bears, suggesting Ireland as the most likely location for their early existence. Despite the lack of consensus in the scientific community, she emphasizes the importance of exploring alternative theories and the potential Significance of the thyroid gland in controlling various physiological functions and driving rapid evolutionary changes

  • 00:00:00 In this section of the YouTube podcast titled "Susan Crockford: Failed polar bear narrative; also their origin/evolution | Tom Nelson Pod #187," Susan Crockford, a zoologist and specialist in evolution and Arctic ecology, discusses recent polar bear population surveys in Hudson Bay. She explains that reports from Western Hudson Bay, which showed a decline in polar bear numbers, received widespread media attention. However, that decline was not statistically significant, and the increase in the Southern Hudson Bay population was largely ignored by those promoting the "narrative" of polar bears suffering due to climate change. Crockford emphasizes the need for a more accurate understanding, as neighboring populations with similar conditions are experiencing opposing trends
  • 00:05:00 In this section of the YouTube video titled "Susan Crockford: Failed polar bear narrative; also their origin/evolution | Tom Nelson Pod #187", Susan Crockford discusses the challenges in accurately estimating the population of polar bears and how the current population estimates might be much higher than previously thought. She mentions that researchers have obtained different results in neighboring populations, which could significantly impact population management and counting efforts. Using estimates from experts in the 1960s, Crockford suggests that the number of polar bears was likely between 10,000 and 12,000. However, the latest official estimate is about 26,000, indicating a considerable increase in numbers. Despite this, some researchers prefer to underestimate population sizes to downplay the impact of climate change on polar bear populations. The 26,000 global population estimate for polar bears has remained the same since 2015, even though new estimates suggest an increase. Crockford expresses skepticism about claims that there is no way to know the population size in the 1960s or that it may have been much higher, as some estimates indicate. She believes that the lower bound of 10,000 is reasonable but that the upper limit of 15,000 might be too conservative, considering low numbers found in specific areas. The ongoing debate focuses on reconciling these different estimations while acknowledging the difficulties of accurately counting polar bear populations
  • 00:10:00 In this section of the podcast titled "Susan Crockford: Failed polar bear narrative; also their origin/evolution," speaker Tom Nelson discusses the disagreement between Inuit communities and polar bear specialists regarding polar bear populations. Nelson argues that the Inuit, who have observed an increase in bear sightings and the impact on their daily lives, should be trusted over the polar bear specialists who believe the population is declining. These specialists argue that bears are coming onto land due to the disappearing sea ice, but the Inuit, with their long-standing experience and knowledge, provide evidence of increased bear numbers. Despite the estimated population between 500 and 1,000, the real number is believed to be closer to the higher end. Hunting, primarily in Canada and Greenland, is the main cause of polar bear deaths, and regulations are in place. The decline in interest in using polar bears as a symbol for the climate change narrative may be due to its failed predictions about sea ice and the bears' impact
  • 00:15:00 In this section of the YouTube video, Susan Crockford discusses the polar bear research community and their continued commitment to linking CO2 emissions to polar bear issues for the sake of research funding and employment opportunities. The community's pressure toward maintaining the polar bear endangered species listing results in a strong narrative and consensus on the issue. Dissenting voices, like that of Mitch Taylor, who questioned the legitimacy of some polar bear arguments, were pushed out in 2009. Tom Nelson, the video's host, shares his own experience of being dropped from the University of Victoria as an adjunct professor in 2019, which he attributes to a paper written by two polar bear specialists and climate change advocates that criticized him
  • 00:20:00 In this section of the podcast, Susan Crockford discusses her experience being labeled as a denier of polar bears and climate change due to her blogs and research. The labeling led to journalists avoiding her, as they were threatened with backlash. Crockford expresses appreciation for Tom Nelson's support and admires his courage in addressing the issue. She reflects on the importance of upholding the principles of science and not disregarding past research to fit a new narrative. Crockford emphasizes the significance of her contributions in raising awareness about manipulation in climate change rhetoric and encourages critical thinking among the public. Furthermore, she mentions her new book on polar bear evolution, highlighting the physical differences between polar bears and their ancestor, the brown bear
  • 00:25:00 In this section of the podcast, Susan Crockford discusses her research on the evolution of polar bears from brown bears. She explains that while it is commonly believed that evolution is a slow process taking tens of thousands to hundreds of thousands of years, it is now widely accepted that species can evolve quickly within 10 to 20 generations to survive in new habitats. She describes an experiment conducted on Russian foxes in the 1950s as an example of rapid transformation. The foxes, bred for their fur, were kept in cages and became agitated, causing an unpleasant environment for both the animals and farmers. A geneticist decided to selectively breed the animals that showed less fear of human contact, using the "fearless" animals to start a new breeding population. Through this aforementioned selection process, the foxes' behaviors changed significantly over several generations
  • 00:30:00 In this section of the podcast, podcast host Tom Nelson discusses an experiment conducted in the 1950s and 1960s where foxes were bred in captivity and within a few generations, several significant changes occurred. The animals' coats transformed from black to bicolor, their behavior became more amenable to humans, and their reproduction timing shifted. The experiment's geneticist was perplexed by the rapid changes, as he believed genetic mutations were the cause but couldn't explain how so many changes could happen simultaneously. However, the researcher wasn't necessarily seeking these specific changes and wrote about the findings in the Journal of Heredity in 1979. After discovering all the alterations in the foxes and the things that change between wild and domesticated species, Nelson concluded that the common factor was thyroid hormone. Thyroid hormone plays a crucial role in embryonic development and gene regulation, allowing for changes in gene output without the gene mutating itself
  • 00:35:00 In this section of the YouTube video titled "Susan Crockford: Failed polar bear narrative; also their origin/evolution | Tom Nelson Pod #187", Susana Crockford discusses the importance of the thyroid gland in controlling various physiological functions in animals, including temperature regulation, metabolism, reproductive timing, fetal and postnatal growth, and hair production and growth. She also shares her hypothesis that hormone production, including that of the thyroid gland, follows a pulsatile pattern with individual variations. Crockford uses the example of fearlessness in Arctic foxes and posits that selecting for this trait results in the rapid emergence of related traits as the entire thyroid rhythm is interconnected, influencing several other physiological processes
  • 00:40:00 In this section of the podcast, Susan Crockford discusses her controversial theory on the origin and evolution of polar bears, which was the focus of her PhD thesis in 2004 and resulted in several peer-reviewed papers. Although not yet proven, the theory is testable, as Crockford suggests the need for a technology like an insulin pump to measure thyroid hormone levels in small amounts. She believes that by comparing the hormone levels of polar and brown bears, valuable insights into their evolutionary differences could be gained. Currently, brown bears held in zoos potentially offer an opportunity to investigate this theory due to their proximity and accessibility for research
  • 00:45:00 In this section of the podcast, Susan Crockford discusses her theory regarding the origin and evolution of polar bears, specifically focusing on the role of thyroid hormones in their development. Although some researchers are exploring this area, it is not widely accepted in the scientific community yet. Crockford writes about her theories in detail in her Polar Bear Evolution book, with the core of the theory being in the middle of the book. She proposes that polar bears likely emerged between 185,000 and 450,000 years ago based on glacial and interglacial periods. Assuming that a bear specialized for living on sea ice would have arisen during a glacial period, she suggests that the polar bear's emergence occurred during Marine Isotope Stage 16, 12, or 6 as these were the most severe glacial periods. The fossil record and severe glacial periods are not taken into account in some estimates, and Crockford's theory assumes that the emergence of polar bears happened during a severe glacial period when glaciers would have been impacting land masses, making it less viable for brown bears to survive there
  • 00:50:00 In this section of the podcast, Susan Crockford discusses the possible origins and evolution of polar bears, suggesting Ireland as the most plausible location for the species' early existence around 140,000 years ago. Brown bears lived in Ireland before that time, but they didn't exist there before, indicating the speciation event likely occurred near that timeline. The ice from the Arctic pushed brown bears onto the sea ice, where fearless and curious individuals founding a new population. This population, over a few generations, developed notable differences from the brown bear population, including the emergence of white spotted coats, as seen in the Russian foxes' speciation process. Selection favored bears with more white for better hunting success, leading to the eventual polar bear's characteristic white fur
  • 00:55:00 In this section of the podcast, Tom Nelson discusses the contributions of Charles Darwin in the field of evolution and the concept of mutation as the driver of evolution. Darwin did not have the knowledge of genetics during his time, and his theories were based on observing patterns in the natural world. Fast forward to modern times, researchers are studying polar bear evolution using genetics with techniques like nuclear DNA and mitochondrial DNA. However, interpreting the results comes with assumptions, and not everyone is exploring the thyroid hormonal component of polar bear evolution. The speaker also mentions the frustration with the assumption that mutations are the primary cause of evolution and the difficulty in understanding how multiple systems can change simultaneously. A thyroid hormone hypothesis suggests that the same genes that change during speciation are controlled by the amount of thyroid hormone the gene receives, acting as a signal that can alter the gene's output without the gene changing itself. Laboratories can test this idea by manipulating thyroid hormone levels to observe changes in gene outputs

01:00:00 - 01:05:00

In the "Susan Crockford: Failed Polar Bear Narrative; Also Their Origin/Evolution" episode of Tom Nelson Pod #187, Crockford delves into the role of thyroid hormones in species development, emphasizing their significance in the embryo's growth into its specific species. She posits that mother's thyroid hormone secretion plays a crucial role before the embryo's thyroid gland matures. Additionally, they discuss Crockford's theory on self-domestication of animals like wolves, proposing that they took advantage of new human-created habitats. The conversation transitions into polar bear evolution, with Crockford explaining their adaptation to human settlements and the ongoing debate about the order of animal domestication. The episode also underscores the importance of considering climate change in the understanding of polar bear evolution

  • 01:00:00 In this section of the podcast, Susan Crockford discusses the role of thyroid hormones in the development of species, from her book "The Polar Bear Catastrophe that Never Happened." She suggests that a mother's thyroid hormone secretion is primary in causing an embryo to grow into its specific species, despite sharing almost identical genes with another. The thyroid hormone is essential for the growth of an embryo, and its mother's system has control until the embryo's thyroid gland develops. These hormonal differences account for disparities between hybrids, like the mule and horse offspring. Crockford also shares her theory that animals, such as wolves, may have "domesticated" themselves by taking advantage of the new habitats created by early human settlements. This theory challenges the popular notion of humans "catching and raising" wolves into dogs. Her ideas emphasize the importance of the thyroid hormone and its role in shaping species development
  • 01:05:00 In this section of the podcast, Tom Nelson and Susan Crockford discuss the topic of polar bear evolution and domestication of animals. According to Crockford, polar bears were attracted to human settlements due to the scraps left behind, resulting in a new founder population with limited interbreeding. She adds that the rapid change in behavior made them less fearful of humans, leading to their easier adaptation within a human context. The conversation then shifts to the order of animals getting domesticated, with Crockford noting that dogs were the first, followed by pigs, while horses come last, and the reasons for this sequence are still debated among anthropologists. The discussion also touches on the significance of climate change in understanding polar bear evolution

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