Could Wednesday Addams really jolt a frog back to life?
It’s frog dissection day in biology class in the new film The Addams Family. Wednesday Addams thinks she knows what to do. First, she leaps on the table. Then, raising her hands to the sky, she shouts, “Give my creature life!” A device that pulses with electricity now shocks a dead frog waiting to be cut open by the kids’ scalpels. The electricity then bounces from one frog to another. Suddenly, frogs are hopping everywhere — a bit groggy at first, but apparently as alive as ever.
This wild scene isn’t one you’ll be able to recreate on dissection day in your own science class. Electricity can’t jolt the dead back to life. Still, this scene has a lot in common with experiments that happened hundreds of years ago. Back then, scientists were learning how electricity kicks muscles into motion.
Today’s researchers know that electricity can do a lot of amazing things — including help shape the body in the first place.
Skeletal muscles help animals move and breathe. These muscles move because of tension in their fibers. This is called “contraction.” Muscle contractions are triggered by signals that start in the brain. The electrical signals travel down the spinal cord and to the nerves that reach into muscle.
But electric impulses also can come from outside the body. “If you’ve ever shocked yourself on something, your muscles contracted,” explains Melissa Bates. A physiologist at the University of Iowa in Iowa City, she studies how bodies work. Bates focuses on the diaphragm. That’s a muscle that helps mammals breathe.
Shocking a dead frog might make its muscles twitch and get its legs to wiggle. Still, this animal couldn’t hop away, Bates points out. That’s because leg muscles can’t make their own electrical signals.
As soon as a frog hopped away from the source of electricity, the game would be up, she says. “It would fall down and be limp and not able to move.” (This applies to the muscles in a hand, too. And that has left Bates wondering how Thing — a hand without a body — can move at all.)
There are some muscles in the body that can power themselves. Involuntary muscles, such as the heart and muscles that move food through the intestines, supply their own electric impulses. In an animal that has recently died, these muscles continue to function for a while. They can keep contracting for minutes to upwards of an hour, Bates says. But that won’t help the frog make a getaway.
It is possible to use electricity to revive people when they are having a heart attack. For this, people use machines called defibrillators (De-FIB-rill-ay-tors). This isn’t reanimating the dead, though. Defibrillators only work “in something that appears lifeless but still has some of its own electrical potential to reboot that system,” Bates explains. Electricity helps get heartbeats back to a regular rhythm. But this won’t work if the heart has stopped beating entirely (which happens when it has lost its ability to make electrical impulses).
The frogs from biology lab have probably been dead for quite a while and preserved with chemicals. They couldn’t be revived with a defibrillator because they wouldn’t have any heart electrical activity left to jump start.
Wednesday Addams’ froggy antics, while impossible, call to mind experiments that scientists did in the late 1700s. “That was the first hint that electricity is an important part of our body,” says Bates. Back then, people were just starting to see what electricity could do. Some shocked dead animals to figure out how electricity made muscles move.
The most famous of these experimenters was Luigi Galvani. He worked as a doctor and physicist in Italy.
Galvani mostly worked with dead frogs, or rather their bottom halves. He would slice open the frog to reveal the nerves that ran from the spinal cord to a leg. Then, to study how a frog’s muscles respond to electricity, Galvani would wire up the frog’s leg under different conditions.
By this time, scientists already knew that an electric shock would make muscles twitch. But Galvani had questions about how and why that happened. For example, he wondered if lightning would do the same thing as the electricity made by his machine. So he hooked up one animal to a wire that snaked outside to a thunderstorm. He then watched those frog legs dance when they were jolted by lightning — just as they did with his machine’s electricity.
Galvani also noticed that when a wire connected a leg muscle to a nerve, the muscle contracted. This led him to hypothesize an “animal electricity” inside creatures. Galvani’s research inspired many scientists and created a new field of study that investigated electricity in the body.
Such work also inspired fiction. “There is an imagination that followed Galvani’s experiments,” says Marco Piccolino at the University of Ferrara. He’s neurologist, a scientist who studies the body’s nervous system. Piccolino, based out of Pisa, Italy, is also a science historian. Galvani’s experiments and those of the scientists that followed him helped inspire Mary Shelley’s novel Frankenstein, Piccolino says. In her classic book, a fictional scientist gives life to a human-like creature.
Nobody has figured out yet how to use electricity to make the dead come back to life. But some researchers have figured out how to hack cells’ electric signals to change how animals develop.
Michael Levin works at Tufts University in Boston, Mass, and at the Wyss Institute of Harvard University in Cambridge, Mass. As a developmental biophysicist, he studies the physics of how bodies develop.
“All of the tissue in your body is communicating electrically,” he notes. By eavesdropping on those conversations, scientists can crack the cells’ code. They also can play back the electrical messages in other ways to alter the body’s development, he says.
Cells in the body have an electric potential (a difference in charge) across their membranes. This potential comes from how charged ions are arranged inside and outside of cells. Researchers can mess with this using chemicals that change where the ions can go.
Manipulating these signals has allowed Levin’s team to tell a frog tadpole to grow an eye in its gut. They also have gotten brain tissue to grow elsewhere in a frog’s body. They’ve even been able to tell nerves how to connect to a newly attached eye.
Everyone thinks genes determine how an animal develops. But “that's only half the story,” Levin says.
Bioelectricity could hold the power to fix birth defects, regrow organs or reprogram cancerous cells. Levin and his colleagues have already fixed birth defects in tadpoles. And they picture a day when electricity could be used similarly in medicine.
This is far from Wednesday Addams and her reanimated frogs — but so much better.
biology The study of living things. The scientists who study them are known as biologists.
cell The smallest structural and functional unit of an organism. Typically too small to see with the unaided eye, it consists of a watery fluid surrounded by a membrane or wall. Depending on their size, animals are made of anywhere from thousands to trillions of cells.
chemical A substance formed from two or more atoms that unite (bond) in a fixed proportion and structure. For example, water is a chemical made when two hydrogen atoms bond to one oxygen atom. Its chemical formula is H2O. Chemical also can be an adjective to describe properties of materials that are the result of various reactions between different compounds.
colleague Someone who works with another; a co-worker or team member.
contract To activate muscle by allowing filaments in the muscle cells to connect. The muscle becomes more rigid as a result.
develop (in biology) To grow as an organism from conception through adulthood, often undergoing changes in chemistry, size and sometimes even shape.
developmental (in biology) An adjective that refers to the changes an organism undergoes from conception through adulthood. Those changes often involve chemistry, size and sometimes even shape.
diaphragm (in biology) The muscular wall in mammals that separates the thorax from the abdomen. In breathing, its contractions open up the thorax, inflating the lungs.
dissection The act of disassembling something to examine how it is put together. In biology, this means opening up animals or plants to view their anatomy.
electricity A flow of charge, usually from the movement of negatively charged particles, called electrons.
electric potential Commonly known as voltage, electric potential is the driving force for an electrical current (or flow of electrons) in a circuit. In scientific terms, electric potential is a measure of the potential energy per unit charge (such as electron or proton) stored in an electric field.
fiction (adj. fictional) An idea or a story that is made-up, not a depiction of real events.
field An area of study, as in: Her field of research was biology.
gene (adj. genetic) A segment of DNA that codes, or holds instructions, for a cell’s production of a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.
heart attack Permanent damage to the heart muscle that occurs when one or more regions of it become starved of oxygen, usually due to a temporary blockage in blood flow.
hypothesis (v. hypothesize) A proposed explanation for a phenomenon. In science, a hypothesis is an idea that must be rigorously tested before it is accepted or rejected.
involuntary An action that is not done intentionally.
ion (adj. ionized) An atom or molecule with an electric charge due to the loss or gain of one or more electrons. An ionized gas, or plasma, is where all of the electrons have been separated from their parent atoms.
lightning A flash of light triggered by the discharge of electricity that occurs between clouds or between a cloud and something on Earth’s surface. The electrical current can cause a flash heating of the air, which can create a sharp crack of thunder.
mammal A warm-blooded animal distinguished by the possession of hair or fur, the secretion of milk by females for feeding their young, and (typically) the bearing of live young.
membrane A barrier which blocks the passage (or flow through) of some materials depending on their size or other features. Membranes are an integral part of filtration systems. Many serve that same function as the outer covering of cells or organs of a body.
muscle A type of tissue used to produce movement by contracting its cells, known as muscle fibers. Muscle is rich in protein, which is why predatory species seek prey containing lots of this tissue.
nerve A long, delicate fiber that transmits signals across the body of an animal. An animal’s backbone contains many nerves, some of which control the movement of its legs or fins, and some of which convey sensations such as hot, cold or pain.
nervous system The network of nerve cells and fibers that transmits signals between parts of the body.
neurology A research field that studies the anatomy and function of the brain and nerves. People who work in this field are known as neurologists (if they are medical doctors) or neuroscientists if they are researchers with a PhD.
organ (in biology) Various parts of an organism that perform one or more particular functions. For instance, an ovary is an organ that makes eggs, the brain is an organ that makes sense of nerve signals and a plant’s roots are organs that take in nutrients and moisture.
phenomenon Something that is surprising or unusual.
physics The scientific study of the nature and properties of matter and energy. Classical physics is an explanation of the nature and properties of matter and energy that relies on descriptions such as Newton’s laws of motion. Quantum physics, a field of study that emerged later, is a more accurate way of explaining the motions and behavior of matter. A scientist who works in such areas is known as a physicist.
physiologist A scientist who studies the branch of biology that deals with how the bodies of healthy organisms function under normal circumstances.
scalpel A type of special knife used to open the body, usually to perform surgery.
skeletal muscle Muscles that help an animal move and whose movements can be directed voluntarily. (The heart, also a muscle, moves involuntarily.)
species A group of similar organisms capable of producing offspring that can survive and reproduce.
spinal cord A cylindrical bundle of nerve fibers and associated tissue. It is enclosed in the spine and connects nearly all parts of the body to the brain, with which it forms the central nervous system.
tissue Made of cells, it is any of the distinct types of materials that make up animals, plants or fungi. Cells within a tissue work as a unit to perform a particular function in living organisms. Different organs of the human body, for instance, often are made from many different types of tissues.
voltage A force associated with an electric current that is measured in units known as volts. Power companies use high-voltage to move electric power over long distances.
Journal: D. J. Blackiston and M. Levin. Ectopic eyes outside the head in Xenopus tadpoles provide sensory data for light-mediated learning. Journal of Experimental Biology. Vol. 216, February 27, 2013, doi:10.1242/jeb.074963.
Journal: M. Piccolino. Animal electricity and the birth of electrophysiology: The legacy of Luigi Galvani. Brain Research Bulletin, Vol. 26, July 1998. doi: 10.1016/S0361-9230(98)00026-4.