If you’ve had a baby, know a baby, or even have just seen a baby, you will agree: they’re not capable of doing much on their own, right?

Well what if that wasn’t entirely true? What if newborn babies were capable of doing plenty of things from the off?

Now, don’t be fooled: there’s no suggestion that your newborn is capable of driving a car, or running for president. But the behaviours that are fundamental for survival? Across the animal kingdom, researchers have proven that newborn abilities are innate and etched on the genome, not learned as some scientists previously thought.

Helping to solve the centuries old nature versus nurture debate, a team of neuroscientists discovered that many of the neural pathways required for animals to survive are present at birth.

In a recent paper published in the journal Nature Communications, a team of researchers led by neuroscientist Dr Dániel L. Barabási explained the study’s desire to question whether learning activities are really responsible for newborns abilities:

“The complex neuronal circuitry of the brain develops from limited information contained in the genome. After the genetic code instructs the birth of neurons, the emergence of brain regions, and the formation of axon tracts, it is believed that temporally structured spiking activity shapes circuits for behavior.

Here, we challenge the learning-dominated assumption that spiking activity is required for circuit formation by quantifying its contribution to the development of visually-guided swimming in the larval zebrafish.”

Often used in research because of their unlikely genetic similarity to humans, the specific physiology of zebrafish made them perfect for this study.

In an interview with IFLScience, the study’s co-author Dr Florian Engert, Professor of Molecular and Cellular Biology at Harvard University, explained that they didn’t really know what to expect:

“How much developmental activity is necessary for circuit assembly was just not known. The inspiration was to do it in a larval zebrafish, because that’s currently the only vertebrate where you can block all activity throughout development reversibly.

It wasn’t an experiment where we had an expectation for the outcome. We were just open for anything here.”

The study used a drug called tricaine, mixed into water, to anaethatise larval zebrafish. This was the only stage of development in which the drug would be effective: it would have killed older zebrafish because of their requirement to eat and breathe.

However, at the larval stage, the zebrafish were able to absorb air and food through their skin, ensuring their survival:

“Testing whether these activity-dependent components of development are truly necessary for the maturation of functional neuronal circuits requires the ability to reversibly block all spiking activity throughout the period of brain formation – an intervention previously lethal at birth.

We have overcame this challenge by utilizing the reversible sodium channel blocker tricaine to pharmacologically block all action potentials during the four days in which the central nervous system of the larval zebrafish is formed.”

The three days of development that the fish ‘missed’ through their anaesthetic was once thought to be fundamental to the formation of vital neural pathways. In particular, the scientists expected that abilities related to the optomotor response (reflexes linked to what an animal can see) would be inhibited, as the fish were kept in the dark.

However, after the zebrafish woke up, the researchers reported that there seemed to be no negative effects on their observed abilities. In fact, there was no difference between the test subjects and their untested counterparts:

“We found that visual experience had no effect on the emergence of the optomotor response (OMR) in dark-reared zebrafish. We then raised animals while pharmacologically silencing action potentials with the sodium channel blocker tricaine.

After washout of the anesthetic, fish could swim and performed with 75–90% accuracy. Brain-wide imaging confirmed that neuronal circuits came ‘online’ fully tuned, without requiring activity-dependent plasticity.

The zebrafish could not only perform complex visuomotor behaviors, but they also exhibited fully functional and appropriately tuned neuronal cell types whose response properties were no different from those found in normally reared animals.”

While in humans development is much more complicated, since it requires a lot of social and cultural learning, one thing from this study seems to apply across the animal kingdom.

When it comes to the functional neural pathways (that is, the parts of the brain used to fulfil the functions required for our survival), learning is seemingly not required. This study suggests that these behaviours are a part of our genome.

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