Dani Crain

Dani Crain

PhD Candidate

Baylor University


In her PhD, Dani Crain spent most of her time cutting apart layers in whale earwax.

Yes, whales have ears! But unlike you and me, they can’t clean their ears. So earwax builds up in their ear canals over their entire lives, forming layers like tree rings. In my PhD (expected graduation in 2021), I use this plug of earwax, or earplug, to investigate the long-term trends in stress and sex hormones in baleen whales.

I am an ‘‘Endochronologist,’’ because I am broadly interested in using using animal bits that grow over time (like claws and baleen and baleen whale earwax!) to track how the environment impacts trends in stress, reproduction, diet, and location. The biomarkers I use to investigate this are steroid hormones (like progesterone, testosterone, cortisol, and corticosterone) and nitrogen/carbon stable isotopes. I have been a researcher with the Alaska Department of Fish & Wildlife and am currently a researcher with Fisheries and Oceans Canada.

I am always interested in talking science, please contact me if you’d like to chat!

In my off time, I enjoy powerlifting, knitting, drinking copious amounts of coffee, reading science-fiction/fantasy, baking, and cooking.


Curriculum Vitae

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I am investigating the long-term trends in stress and reproductive hormones in baleen whales using their waxy earplugs, which form layers like tree rings. Moreover, I aim to make STEM graduate school and careers more inclusive (see Projects).

I am broadly interested in using animal’s steroid hormones to help us learn more about how they respond to their environment.

Honors & Awards:

  • Baylor Graduate Student Fellowship, 2015 - 2020
  • C. Gus Glasscock, Jr. Endowed Fund of Excellence in Environmental Sciences, 2016
  • Outstanding Graduate Student Instructor Award, 2017
  • C. Gus Glasscock, Jr. Endowed Fund of Excellence in Environmental Sciences, 2018
  • World Marine Mammal Conference Audience Favourite Presentation Award, 2019
  • Winner of Baylor University Graduate Research Showcase, 2020
  • Society of Comparative and Integrative Biology Division of Comparative Endocrinology Aubrey Gorbman Best Student Paper Award Nominee, 2020, 2021


  • Longterm environmental trends
  • Marine mammal biology
  • Endocrinology
  • Reproductive physiology


  • PhD Candidate in Biology, 2021

    Baylor University

  • M.E.M. in Coastal Environmental Management, 2012

    Duke University

  • B.Sc. in Ecology & Evolution, 2009

    University of California, Santa Cruz


Researcher with Fisheries and Oceans Canada (Present): I am currently analyzing and writing peer-reviewed manuscripts about steroid hormones, stable isotopes, and trace elements in marine mammal matrices (like baleen).

Researcher with the Alaska Department of Fish & Game (Oct. 2020-Oct. 2021): I worked with ADFG to analyze and publish a manuscript about steroid hormones and carbon and nitrogen stable isotopes in the claws of bearded and ringed seals. This work has been published (see publications).

PhD research:

I reconstruct baleen whale lifetimes using the hormones in their earwax. Whales produce earwax which builds up in their ear canals over time. This earwax forms a plug that, when cut in half, shows layers similar to tree growth rings (above). Each of these layers correspond to 6 months of time and begin forming in utero until death. This means we can assign a specific age and year to each layer in the earplug. We use the hormones from these layers to show when an individual whale experiences stress, when they reach sexual maturity, and when they are pregnant. Big picture this allows us to look at the environment at the time these animals were alive. To date, we have 150 years of data from the mid-1800s to present day from more than 40 individual baleen whales, including blue, fin, humpback, gray, and minke whales.

The ability for researchers to extract hormones and contaminants from baleen whale earplugs is still very new. Some of the basic questions, like how hormones in the earplugs vary in different tissues is still unknown. Furthermore, much of the known life history for these animals is from long-term observational datasets, which can be subject to sampling biases. Earplugs do not have these same limitations.

Therefore, the focus for my PhD is: 1) assessing steroid hormone concentrations in the earplug, baleen, and blubber of the same individual baleen whales, 2) determining how three stress biomarkers vary in the same layers of an earplug of baleen whales, and 3) analyzing progesterone concentration in earplug layers to determine how many pregnancies a whale experiences in her lifetime.


Research Covered in the News:
- The Atlantic: ‘‘The History of the Oceans Is Locked in Whale Earwax’’
- National Geographic: ‘‘Earwax reveals how humans have changed whales’ lives’’
- Baylor University: ‘‘Baylor Professors Use Whale Earwax to Reconstruct Whale Stress Levels Spanning More Than a Century’’
- Natural History Museum - London: ‘‘Whale earwax reveals just how much human activity can stress out marine mammals’’
- Natural History Museum - London Video: What can we learn from whales' earplugs?
- ARS Technica: ‘‘Whales are stressed out by climate change, and it shows in their earwax’’
- Smithsonian Magazine: ‘‘We Know How Stressed Whales Are Because Scientists Looked At Their Earwax’’


STEMculture Podcast

STEMculture Podcast is a podcast focused on improving the culture of STEM by talking about topics that affect graduate students, postdocs, early career researchers and more.

Graduate Student Success

Graduate students need more development of skills and techniques to be successful in their masters or PhD. Here, I share the techniques and skills that have worked for me.

Hormones from the right and left earplugs of baleen whales

Are trends in hormones from the right and left earplugs of the same individual baleen whale the same?

Pregnancy events from earplugs

Progesterone, the pregnancy hormone, plays a huge role in population dynamics when extracted from earplugs.

CMHD/EEO Graduate Student Society (CEGSS)

A graduate student society to increase camaraderie among graduate students of the Biology Department of Baylor University for the two tracks: cellular, molecular, health & disease/ecology, evolution, & organismal biology.

Burning the candle from both ends

There are three stress biomarkers that the marine mammal field is interested in right now: cortisol, corticosterone, and aldosterone.

Hormone comparison between right and left baleen whale earplugs

Do hormones in the right and left earplugs from the same individuals match? What does ‘‘baseline’’ mean for hormones?

Hormones and stable isotopes in claws of ringed and bearded seals.

Ringed and bearded seal claws have dark and light bands which correspond with the winter (dark) and summer (light). Sampling these bands provides ~10 years of hormone and stable isotope data.

Steroid hormones in three biological matrices from the same individuals

I examine stress and sex hormones in the earplug, baleen, and blubber of the same individuals to ascertain the consistency of hormone deposition.

Women in Science and Engineering at Baylor University

Women in Science and Engineering (WISE) at Baylor Univerity: We aim to support each other, make STEM more inclusive, and mentor new faculty.

Present Your PhD

Present Your PhD (PyPhD): A graduate student organization bringing the excitement of science into classrooms and the community!


Before starting my PhD in Biology at Baylor University in August 2015, I was an adjunct professor at Cosumnes River College, where I taught Anatomy & Physiology and Foundations of Biology, and California State University Sacramento, where I taught Human Reproductive Physiology.

Currently, I am a teacher of record and have taught lab courses for anatomy & physiology for nursing track students as well as introductory biology at Baylor University. In Spring 2017 I won the Outstanding Graduate Student Instructor Award while teaching Bio 2401, Anatomy & Physiology.

From left to right: Biology Department Graduate Program Director Dr. Ryan King, Acting Vice Provost for Administration Dr. Gary Mortenson, myself (Dani Crain), and Vice Provost and Dean of Baylor Graduate School Dr. J. Larry Lyons after the award ceremony.