A New Model of Human Origins in Africa; How Do Volcanoes Respond to Glaciation?; Fate of Aquatic Pesticides Used for Invasive Species Control; Breeding for Tree Crop Improvement

For Wednesday 30 August 2023

Hi WN@TL Fans,


Origins are of the essence:  there’s good reason Genesis opens The Book.  We use origin stories to help explain how we are today and where we’re heading tomorrow.


The stories of the origins & migrations of humans can be empirically revealed in several ways, including in fossils of our bones, in structures of our speech, and in sequences of our DNA.  If one assumes a human generation time of 20 years, then a millennium spans 50 generations (for context, Harold II of Hastings fame was born in 1022);  100,000 years encompasses 5,000 generations.  That’s a lot of time for mutation, for migration, and for mixing; luckily, researchers such as Aaron Ragsdale have math far beyond my arithmetic to help parse them out and to braid them together.


We contain multitudes.  We also generate many possible versions of our emergence.  Tonight we get to sift and sort through competing ideas of how humans arose in Africa, and hear about new evidence & analyses that help us see a little clearer and a little farther.


On August 30 Aaron Ragsdale of Integrative Biology will speak on his research published in Nature on June 13 entitled “A Weakly Structured Stem for Human Origins in Africa.   Nature also published an overview article by Elsabé BritsA New Model of Human Origins in Africa: https://www.nature.com/articles/d44148-023-00145-9


Description: It is now well-established that our species, Homo sapiens, emerged within Africa over the past hundreds of thousands of years before dispersing across the globe. However, apart from recent genetic discoveries of recontact between Neanderthals, Denisovans and humans, there is large uncertainty about the size, structure and connectivity of human populations during those early periods. Because the fossil record from this time is sparse, we rely on genomic data from present-day and ancient individuals to reconstruct the details of past population structure.


Here, we present a recent progress in our understanding of deep human history using genetic data from geographically and genetically diverse populations. We contrast models of archaic admixture with population structure, and discuss open questions in the field of human evolutionary history and paleoanthropology.


Bio: Aaron Ragsdale is an assistant professor in the Department of Integrative Biology. His research focuses on population genetic theory and computation methods for learning about demographic and evolutionary history from genomic data.


Explore More:  In this paper, we use geographically and genetically diverse populations across Africa and Eurasia to reconstruct detailed demographic models for our species in the deep past. We find that a model that includes long-lasting population structure, with populations connected by ongoing migration, provides the best fit to the genetic data. In contrast to other recent studies, we do not find evidence for a substantial contribution from an unidentified “ghost” population within Africa (akin to Neanderthal and Denisovan contributions in Eurasia). This work is in collaboration with my former postdoc advisor Simon Gravel, at McGill University, Brenna Henn and Tim Weaver at UC Davis, and others.

Ragsdale Lab:  https://apragsdale.github.io

Study Offers New Twist in How the First Humans Evolved:  https://www.nytimes.com/2023/05/17/science/human-origins-africa.html

Did Early Humans Interbreed with a ‘Ghost’ Population?: https://www.nationalgeographic.com/premium/article/did-early-humans-interbreed-with-a-ghost-population



On September 6 we move into the new academic year with a talk on volcanoes in Chile with Sally Stevens and Pablo Moreno-Yaeger of Geosciences.


Title:  How Do Volcanoes Respond to Glaciation?


Description:  How does glaciation impact volcanic activity? The Andean Southern Volcanic Zone in Chile consists of over 30 active continental arc volcanoes, including some of the most hazardous volcanoes in the country. These volcanoes were engulfed by a large, 1-2 km thick continental ice sheet approximately ~18 thousand years ago followed by rapid deglaciation that ended ~15 thousand years ago. We present geochronological and geochemical data from volcanoes Mocho-Choshuenco and Puyehue Cordón-Caulle to investigate how these individual volcanoes responded to crustal stress changes from ice loading and unloading of the Patagonian Ice Sheet.


Bio: Pablo Moreno-Yaeger is a Chilean Ph.D. Candidate at the University of Wisconsin-Madison, advised by Professor Brad Singer. Pablo was born in San Bernardo, Chile and graduated from Universidad de Chile in Geology. After graduation, Pablo taught undergraduate Geoscience courses in southern Chile. He moved to Madison and earned his Master’s in Geoscience at UW-Madison.


Bio: Sally Stevens is a Ph.D. student at the University of Wisconsin-Madison, studying igneous petrology and geochronology with Dr. Brad Singer. She earned her Bachelor’s in Geology at University of California Santa Barbara and worked at the USGS California Volcano Observatory prior to earning her Master’s in Geoscience at UW-Madison.


Explore More:

Ice Forcing in Arc Magma Plumbing Systems (IF-AMPS): https://ui.adsabs.harvard.edu/abs/2021AGUFM.V14B..01S/abstract

Evolution of magma storage conditions spanning the last glacial-interglacial transition, Mocho-Choshuenco Volcanic Complex, Chile:




On September 13 Christy Remucal of Civil & Environmental Engineering will speak on “The Fate of Aquatic Pesticides Used for Invasive Species Control in Lakes & Rivers.”


Description:  Pesticides are commonly used to control invasive species, such as Eurasian watermilfoil and the sea lamprey, in lakes and rivers in Wisconsin. It is important to understand how long these chemicals last in surface waters to limit impacts on non-target organisms. This presentation will explore the processes that influence the lifetime of several commonly used aquatic pesticides by relating laboratory experiments with field measurements. In addition to providing better understanding of the fate of these specific chemicals, this research provides insight into the behavior of other related organic chemicals in our surface waters.


Bio:  Associate Professor Christy Remucal leads the Aquatic Chemistry group at the University of Wisconsin-Madison and is the Director of the Water Science and Engineering Laboratory. She is a faculty member in the Department of Civil & Environmental Engineering, the Environmental Chemistry & Technology Program, and the Limnology & Marine Science Program. She holds an MS (2004) and a PhD (2009) in Civil & Environmental Engineering from the University of California, Berkeley, and a BS (2003) in Environmental Engineering Science from Massachusetts Institute of Technology. Before joining the UW-Madison faculty, Christy completed a post-doc in the Institute for Biogeochemistry and Pollutant Dynamics at the Swiss Federal Institute of Technology.


Explore More:

Lab website: https://remucal.engr.wisc.edu/index.html

DNR’s invasive species page: https://dnr.wisconsin.gov/topic/Invasives



On September 20 Scott Brainard of the Savanna Institute will speak on his research with the Savanna Institute.


Bio:  Scott coordinates Savanna Institute’s work on tree crop improvement, with a particular focus on building genetic repositories for multiple agroforestry species. A former organic vegetable farmer, Scott received his MSc degree in Plant Sciences from Wageningen University, and his PhD in Plant Breeding and Plant Genetics from the University of Wisconsin–Madison. He is also a postdoctoral researcher in the lab of Dr. Julie Dawson at UW–Madison. Scott is passionate about perennial crop improvement that supports more sustainable agroforestry systems.


Explore More:

Savanna Institute Tree Crop Improvement: https://www.savannainstitute.org/tree-crop-improvement/

Upper Midwest Hazelnut Development Initiative: https://www.savannainstitute.org/tree-crop-improvement/




Hope to see you soon — in person, by YouTube livestream or by Zoom — at Wednesday Nite @ The Lab.


Tom Zinnen
Biotechnology Center & Division of Extension, Wisconsin 4-H



Please share this missive with your friends & neighbors. 


If you’ll be watching the Zoom for the first time, please register for the WN@TL Zoom at go.wisc.edu/240r59. 

If you’ve already registered for a previous WN@TL zoom this year, you’re good—you don’t have to register again.

Continue to use the link found in the confirmation message Zoom sent you when you first registered.

WN@TL begins at 7:00pm Central.

You can also watch the web stream at the WN@TL YouTube channel.



UW-Madison:  5.9 million owners, one pretty good public land-grant teaching, research and extension university.


Visit UW-Madison’s science outreach portal at science.wisc.edu for information on the people, places & programs on campus that welcome you to come experience science as exploring the unknown, all year round.



Here are the components of the WN@TL User’s Guide:

  1. The live WN@TL seminar, every Wednesday night, 50 times a year, at 7pm CT in Room 1111 Genetics Biotech Center and on Zoom at go.wisc.edu/240r59
  2. The WN@TL YouTubechannel
  3. WN@TL on the University Placebroadcast channel of PBS Wisconsin


Park for a small fee in Lot 20, 1390 University Avenue, Madison, WI


Archive of Past Talks Upcoming Talks



In partnership with

Wisconsin Alumni Association | UW-Madison Biotechnology Center

Division of Extension | PBS Wisconsin | UW Science Alliance