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Chase Mendenhall

April 17, 2019 by wpengine

Defeating Thanos and his Malthusian Mission of Population Control

Thomas Robert Malthus penned an essay on population growth in 1798 that mathematically demonstrated the relationship between food and human population. Malthus argued that whenever food supply increases, population rapidly grows to eliminate the abundance resulting in perpetual human suffering unless we control human population. From bacteria growing in a petri dish to lynx feeding on hares, Malthus’ essays on the principle of population are essential tools to ecologists forecasting population changes relative to resources. Malthus’ ideas also greatly influenced the early architects of the theory of evolution and sparked a great deal of debate on the improvement of society, birth rates, and forced sterilization. In fact, Malthus’ work is usually taught with care in today’s classrooms and museums because of its role in the development of eugenics and policies that violate human rights.

Malthus died almost 200 years ago, but his legacy continues to appear in debates on sustainability and to inspire apocalyptic plots in science and popular culture. One of the best-known Malthusians was Charles Dickens’ character Ebenezer Scrooge, a miserable old man who suggested that the poor ought to perish sooner rather than later to “decrease the surplus population.” Another example is Aldous Huxley’s novel Brave New World, which was based on a society where people were mass produced using in vitro technology to precisely control the population and people wear their contraception on so called “Malthusian belts.” And, today, Malthus’ latest incarnation comes as the supervillain Thanos in Avengers: Endgame, the next film from the Marvel Cinematic Universe. Over the course of many films, we follow Thanos on a Malthusian mission to wipe out half of all living things to achieve a “perfect balance” in the universe and to eliminate suffering caused by limited resources, a hard choice requiring Thanos’ strong will.

Thanos action figure
Credit: Krikkiat / Shutterstock.com

Despite the fact that wildlife populations repeatedly demonstrate Malthus’ principles of resources and population growth followed by population crashes, nearly all predictions of human suffering forecasted by Malthusians have been proven wrong. The world has generally gotten better with less human suffering as quality of life rises every year since Malthus’ first predictions. For decades apocalyptic predictions by biologists who studied butterflies and bacteria have not been realized because there was no way to account for the innovative abilities of human beings. We humans have radically altered our population and quality of life with inventions like vaccines and chemical fertilizers. Of course, population size and growth underlie nearly every measure of environmental impact in existence, but our ingenuity as a species has tended to prevent human suffering at the apocalyptic scales predicted by Malthusians.

When it comes to innovation for solving big problems caused by human population size and growth, like climate change and extinction, diversity matters. Unlike the world Malthus knew 200 years ago, the source pool for innovative solutions consists of over 7 billion people and includes women, people of color, and others who have been historically suppressed. Diversity leads to more creative and more novel solutions to problems; this has been proven in ecosystems with high amounts of biodiversity, companies with diverse workforces, and, maybe, diverse teams of superheroes defeating Thanos. In the upcoming battle for balance in the Marvel Cinematic Universe, diversity in numbers may be their greatest strength. Is diversity in numbers our greatest strength for solving our biggest problems, like climate change and extinctions?

female Avengers action figures
Credit: Krikkiat / Shutterstock.com

As far as decent ways to balance birth and death on our finite planet, the best strategy seems to be liberating girls and women around the world. In fact, family size shrinks, and quality of life almost always improves when girls are allowed to go to school, when women are allowed to earn money, and when contraceptives are available. Equity for women worldwide sounds like something we can all support regardless of our current planetary boundaries.

Chase Mendenhall is Assistant Curator of Birds, Ecology, and Conservation at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Filed Under: Blog Tagged With: Anthropocene, Chase Mendenhall, ecology, Thomas Robert Malthus

March 11, 2019 by wpengine

A Match Made by Coevolution

Darwin once predicted the existence of a pollinator after examining the star-shaped flower of the orchid Angraecum sesquipedale, a flower whose nectar is at the end of a 30 cm tube. Darwin wrote that “in Madagascar there must be moths with probosces capable of extension to a length of between ten and eleven inches [25.4–27.9cm].” Twenty years after Darwin’s death, his prediction was proven correct with the discovery of a moth, Xanthopan morganii praedicta, which boasted a proboscis 20 cm in length. In 1992, natural history observations of the moth feeding on the extreme flower and transferring pollen provided even more evidence that this plant and insect were tangled in a coevolution that resulted in their extreme morphology.

Coevolution is now a cornerstone of biology and has been well developed through examples of flowering plants and insects, parasites and hosts, predators and prey, and even gut microbiomes and human health. In fact, the influence of closely associated species on each other in their evolution is so ubiquitous one could argue that evolution is coevolution—as the boundary between what is an individual versus a consortia of different species blends as we dive deeper into the units that natural selection is acting upon. The microbiome and human health example helps illustrate the problem of defining an individual, specifically because scientists now think that microbial cells outnumber human cells in your body. Moreover, there is growing evidence this diversity of symbionts on our bodies complete metabolic pathways and serve other physiological functions. Coevolution crisscrosses the natural histories of organisms, creating nuances that sometimes complicate things.

With so much excitement and work surrounding coevolution, it is romantic to stumble across an example of coevolution fit for a kindergarten class. In the collection of birds at the Carnegie Museum of Natural History, we recently finished an analysis of 24 Costa Rican hummingbirds and the pollen types found on their bodies and were reminded of Darwin’s predictions of coevolution over 100 years ago with orchids and moths. The White-tipped Sicklebill (Eutoxeres aquila) is a hummingbird with an extreme bill curve, with an appearance that would remind kindergarteners of Jim Henson’s Gonzo Muppet. Putting this bird next to its favorite food, Centropogon granulosus, illustrates coevolution in an exciting way that doesn’t tangle you up in learning about microbes or imagining other complex ecological relationships. Like Darwin’s orchid and moth, this hummingbird and its preferred flower allow us to see coevolution is all around us.

sicklebill hummingbird and its preferred flower

In an ongoing study at the Carnegie Museum of Natural History’s Section of Birds, we were reminded of the natural history observations and predictions that led to an explosion in the field of coevolution. By studying pollen types collected from hummingbirds in Costa Rica we confirmed that the White-tipped Sicklebill (Eutoxeres aquila) feeds mostly on Centropogon granulosus, a match made by coevolution.

Chase Mendenhall is Assistant Curator of Birds, Ecology, and Conservation at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Filed Under: Blog Tagged With: bird hall, Birds, Botany, Chase Mendenhall, evolution, Section of Birds

February 18, 2019 by Kathleen

The Evolution of Sex and Gender

Speaker: Chase Mendenhall, Curator of Birds, Carnegie Museum of Natural History

In recent decades, plants and animals have revealed far more body and behavior diversity than Darwin ever imagined, especially with coopering to make and raise offspring. From bacteria to bonobos, the fundamental questions of why sex evolved, how bodies are built, and how gender develops from sex will be explored. Using the science of cooperation and natural history evidence, what it means to be an individual, a male, a female, or part of a family or group will be examined. Finally, how natural selection works on groups of organisms to give rise to functional organization like multicellularity, sociality, and civilization will be discussed.

Tagged With: Chase Mendenhall

January 24, 2019 by wpengine

“Amazing, just like a dinosaur!”

Exclamations like this are common among bird biologists, especially when face-to-face with a Pileated Woodpecker or a ferocious Chickadee. Decades of Jurassic Park films have caught us in a tautological trap where birds remind us of dinosaurs—because Hollywood models dinosaurs on birds. From the coordinated flock movements of chickens foraging to the reptilian eyes of a Heron, I often catch myself wanting to say, “Amazing, just like a dinosaur!” But, I restrain myself because my source is mostly Stephen Spielberg.

At the Carnegie Museum of Natural History something that makes the Section of Birds special is its proximity to a world-class collection of dinosaur fossils and the paleontologists they attract. PhD students, like Sam Gutherz from Ohio University, use our collections to study the pulmonary tissue and skeleton of birds to address questions regarding the evolution of the respiratory system in a range of archosaurs.

three people working at desks
Sam Gutherz and colleagues from Ohio University measure bird skeletons at the Carnegie Museum of Natural History to better understand the biology of dinosaurs.

Sam visits natural history museums for both the birds and the dinosaurs—systematically measuring bones and testing questions that ultimately support or refute the connection between birds and dinosaurs. Decades of work by scientists like Sam and his colleagues have built a case using multiple lines of evidence that birds evolved from dinosaurs. In fact, paleontologists have been so successful that bird biologists and Hollywood producers stand on their shoulders.

Chase Mendenhall is Assistant Curator of Birds, Ecology, and Conservation at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Filed Under: Blog Tagged With: bird hall, Birds, Chase Mendenhall, dinosaurs, Hall of Birds, paleontology

November 8, 2018 by wpengine

Ask a Scientist – How Are Birds Like Dinosaurs?

How are birds like dinosaurs? Assistant Curator of Birds, Chase Mendenhall, and Urban Bird Conservation Coordinator, Jonathan Rice, introduce the bird collection in the latest Ask a Scientist. Learn how the Section of Birds works with paleontologists to understand dinosaur behavior.

Ask a Scientist is a video series where we ask our research staff questions about the millions of amazing objects and specimens stored in our museum collection. Tune in on YouTube, and submit your own questions via Twitter @CarnegieMNH!

Filed Under: Blog Tagged With: Ask a Scientist, Birds, Chase Mendenhall, dinosaurs, Section of Birds

November 2, 2018 by wpengine

Doves of Peace

by Chase Mendenhall

two doves on branches

In the wake of a tragedy that took the lives of 11 people in Pittsburgh, we reflect on the the collections housed at the Carnegie Museum of Natural History and find comfort among the doves — symbols of the people of Israel (Song of Songs Rabbah 2:14). Doves are of immense importance symbolizing human souls, sacrifice, and peace.

From the collection we share the European Turtledove (Streptopelia turtur) because it is listed as a species vulnerable to extinction and frequently written about in cultural texts. In fact, it was the stamina and swiftness of the Turtledove that aided Noah in his search for the holy land after the floods (Genesis 8:11). It is also the Turtledove’s loyalty as a mate that mused William Shakespeare to write poetry of an ideal love between a Turtledove and a Phoenix. But, perhaps the most fitting description and scientific namesake of the Turtledove is its cooing call, or the biblical Hebrew word “turtur,” which is a sound of mourning and a call for universal peace.

Together, we mourn the loss of so many innocent lives in Squirrel Hill and hope for peace alongside loved ones and family.

Chase Mendenhall is Assistant Curator of Birds, Ecology, and Conservation at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Filed Under: Blog Tagged With: bird, Birds, Chase Mendenhall

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