Collaborative Research: The Origin of the Large Brains of Cetaceans

鲸目动物(鲸鱼、海豚、海豚)的大脑是地球上有史以来最大的。即使根据身体大小来衡量，鲸目动物的大脑在大小上也仅次于人类。鲸目动物大脑大小的扩大被认为是回声定位和/或神经元数量增加的结果。该项目将利用对鲸目动物化石的研究来确定导致大脑扩张的因素。因为鲸目动物是一群极具魅力的哺乳动物，有着非凡的化石记录，这项研究将以大脑进化为案例，研究对象包括俄亥俄州一所农村STEM学校的高三和高年级学生，以及阿拉斯加的高中生和大学生。学生们将学习一门以鲸鱼、海豹和进化为重点的课程，该课程融合了更广泛的地质学和生物学概念。将利用阿拉斯加州锡特卡科学中心组织的研讨会向公众展示研究结果。这项研究分析了一组最早的鲸目动物化石，以确定有助于大脑大小进化的因素。该项目团队将测试回声定位导致大脑大小增加的假设。这将通过研究化石鲸耳朵形状随时间的变化来实现，以确定高频听力是在什么时候进化的。此外，研究小组将测试鲸目动物大脑的大小增加是否是神经元或其他支持细胞数量增加的结果。这将通过比较活的回声定位鲸和非回声定位鲸的大脑中神经元的数量与大脑中其他细胞的相对数量来完成。这项研究将通过精确定位大脑扩张发生的时间，这种扩张如何与高频听力的开始相关，以及通过量化大脑中细胞的多样性和丰富性来进一步了解鲸目动物的进化。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Cetaceans (whales, dolphins, porpoises) have the largest brains on the planet, ever. Even when scaled for body size, cetacean brains are second only to humans in size. Expansion of brain size in cetaceans has been considered a consequence of echolocation and/or an increase in the number of neurons. This project will use the study of fossil cetaceans to identify factors lead to brain expansion. Because cetaceans are a charismatic group of mammals with an exceptional fossil record, this study will use brain evolution as a case study that engages high school juniors and seniors from a rural STEM school in Ohio, as well as Alaskan high school and college students. Students will take a course focused on Whales, Seals, and Evolution, which integrates broader geological and biological concepts. A symposium organized by the Sitka Science Center in Alaska will be used to present findings to the general public. This study analyzes a collection of the earliest fossil cetaceans to identify factors contributing to the evolution of brain size. The project team will test the hypothesis that the acquisition of echolocation led to increases in brain size. This will be accomplished by studying changes in ear shape in fossil whales over time to identify when high-frequency hearing evolved. In addition, the team will test whether size increases in the cetacean brain are a consequence of increasing numbers of neurons or other support cells. This will be accomplished by comparing the number of neurons within the brains of living echolocating and non-echolocating whales relative to other cells within the brain. This study will further understanding of cetacean evolution by pinpointing when the expansion of the brain occurred, how this expansion relates to the onset of high-frequency hearing, and by quantifying the diversity and abundance of cells within the brain.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.