Leaf-based computer chips, and evidence that two early human ancestors coexisted
Science Magazine Podcast
Deep Dive
Why are current circuit boards in electronics difficult to make more sustainable?
Current circuit boards are made of glass fibers and epoxy, which are highly durable but non-biodegradable, lasting thousands of years in the environment. They also require high temperatures and harsh chemical conditions during manufacturing, making it challenging to replace them with greener alternatives.
What inspired the researchers to use leaves for making circuit boards?
The researchers were inspired by the ubiquity and biodegradability of leaves. They realized that leaves, with their natural fractal structure, could be skeletonized and coated with bio-derived polymers to create a sustainable alternative to traditional circuit boards.
How do the researchers process leaves to use them in electronics?
The researchers skeletonize the leaves, removing the living cells to leave behind a durable, fractal-patterned frame. They then coat this frame with a bio-derived polymer to create a robust, biodegradable substrate for circuit boards.
What are the potential environmental benefits of using leaf-based circuit boards?
Leaf-based circuit boards could significantly reduce e-waste and the carbon footprint of electronics. They are designed for a circular economy, allowing for the recovery of metals and biodegradation of the substrate, which can be reused in biogas production.
Why aren't leaf-based circuit boards currently in use in consumer electronics?
Leaf-based circuit boards do not meet the industry's strict durability standards, which require materials to last for hundreds of years. While they perform well in most tests, they are designed to biodegrade, making them unsuitable for the current industry's long-lasting requirements.
What evidence suggests that Homo erectus and Paranthropus boisei coexisted?
Fossil footprints discovered in the Turkana Basin of Kenya provide evidence of two different species walking on the same shoreline. The footprints, which include a 13-step trackway and three perpendicular prints, suggest that these species were present at the same time, likely 1.6 to 1.4 million years ago.
How do the footprints of Homo erectus and Paranthropus boisei differ?
The footprints of Homo erectus resemble those of modern humans, while Paranthropus boisei's footprints show a more mobile big toe that splayed outward. The arch shape of the footprints also differs, indicating different walking motions between the two species.
Why is it challenging to determine coexistence from skeletal fossils alone?
Skeletal fossils often co-occur within sedimentary sequences spanning tens of thousands of years, making it difficult to pinpoint exact coexistence. Footprints, on the other hand, provide a more precise temporal record, as they are typically formed within hours to days of each other.
What conditions are necessary for fossil footprints to be preserved?
Fossil footprints require a soft mud surface to accept the impressions of feet, followed by a gentle layer of sediment that covers and preserves the footprints. These conditions are more likely to occur in environments like the shores of ancient lakes.
What future research might focus on regarding early human footprints?
Future research could explore additional footprint sites in the Turkana Basin to confirm the coexistence pattern and investigate the environmental factors that attracted both species. Researchers may also look at footprints from earlier time periods to understand the evolution of early human locomotion.
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