Copyright 2022, David G Haskell.
Thank you, it is an honor to join you at Student Conference on Conservation Science, Bangalore, and I’d like to start by offering my thanks to the conference organizers for the invitation to join you and for gathering us to learn from one another and to move forward the exciting science and practices of cause conservation. Conservation science serves a higher purpose – that is to understand the living Earth and thus to enable us to be better members of life’s community. This life community includes the many other species that we share the Earth with and also the vitality of the human community.
I will offer some thoughts on how listening might help us to understand and conserve the living Earth community. I’ll draw examples both from deep time and from the present moment.
Let me start, though, by stating that “listening” takes many forms. We each differ in how we perceive the vibrations of the world and our bodies also have multiple ways of listening.
For many people, but not all, the ear is the primary site of hearing. There, tiny bones, membranes and hairs convert vibrations in air to vibrations in fluid in tubes in the inner ear where they then stimulate hair cells that send signals to the brain. Every ear is different, though. Some pick up vibrations from 20 to 20,000 Hz, the frequency of a bass drum to a high-pitched squeal, but others perceive only the lowest frequencies. A few are insensitive across all frequencies. No human ear hears as wide a range as that of the cat, dog, or many other mammals.
We also detect sound in our flesh, especially in the fingertips where about ten different receptors pick up vibrations. And in our chests where low frequencies are felt. Try listening by resting your hand on a tree trunk or attending to the sensations in your chest.
Listening, then, is a single word that in fact represents a multiplicity of experiences. Our dominant cultures, though, often assume that all can hear with a wide range of sensitivities. This excludes many people. Part of listening, then, must be building a society where all forms of human hearing are welcome and accepted.
To help with this, I have made a written version of this talk available in the chat.
Let us cast our minds back into deep time now and ask where sound came from and what we might learn from these sounds.
It turns out that sound is older than the Earth, older even than atoms. In the primordial plasma of the universe pressures waves flowed through a dense mire of protons, electrons and trapped photons. These were the first pressure waves. The first sounds.
As the universe expanded and cooled, this lava-like furnace cooled and atoms formed. Protons joined electrons. The first elements were born. As they did this, their spacing in the universe retained the mark of the sound waves that had flowed through the dense plasma. These wave marks are discernible still to this day as irregularities in the cosmic microwave background radiation that flows through us at all times. The waves also left their mark in the spacing of atoms. The atoms that formed from the plasma at the peak of the sound waves were squashed together – this is the nature of sound, alternating areas of compression and rarefaction — and these areas of compression eventually became the seeds of the stars. To this day if you measure the spacing between galaxies there is a regularity. They are, on average, 500 million light years apart. This regularity is a reminder of the waveforms of the early cosmos.
Look up at the stars at night and you will see the remnants of the universe’s first sounds.
What does this have to do with conservation? Such stories from ancient times predate the formation of our solar system let alone the evolution of life on earth. I think that the message we can learn from these stories from the early Cosmos is: from it’s very first origins in the universe, sound was a generative force. Sound waves quite literally formed the seeds around which the first Stars formed. They also sculpted the shape of the background radiation of the universe.
When life evolved on planet Earth this creative capacity of sound continued, connecting living beings one to another and opening possibility.
For many living beings, both in the past and in the present sound is one of the primary means of connection from one individual to another. And in every realm of biology we are learning that connection is the stuff of life. And so when sound connects two singing animals, for example, it opens possibility by linking these animals into communicative networks. These communicative networks increase life’s creativity, diversity, and resilience. And so, a story from the physics of the early universe has direct relevance to conservation work in the 21st century. Sound connects. And thus sound is creative.
We understand this very well in our own species. After all sonic communication in spoken language is one of the primary ways that human culture forms. But this is also true for nonhuman beings. You can think as sound as a neurotransmitter within ecosystems – an invisible link between beings, one that acts almost instantaneously and often also at a distance.
What can we learn from the first days of sonic evolution on planet earth? It turns out that sonic communication in the form of songs or calls that are familiar to us today took a very long time to evolve on this planet. A shockingly long time. All single-celled organisms like bacteria or single-celled eukaryotes are sensitive to vibrations in the fluid around them, but as far as we know none of them communicate by sound.
The same was true for the first multicellular animals to evolve on planet earth. During the Great explosion of animal diversity between 650 and 400 million years ago on this planet we have no evidence of any sound making device on any fossilized animal. These animals did have sophisticated eyes, limbs, nervous systems, guts, reproductive systems. So, there was no shortage of raw material for evolution to craft into devices that could make sound. But it seems that in these early years of animal evolution life unfolded in communicative silence. Certainly animals would have made incidental sounds as they swam walked or chewed. But none sung or called, at least as far as we know.
Why was this? It is possible that predation kept a lid on the sonic communication for hundreds of millions of years. All early animals could detect vibrations in water and then later, for those animals living on land, vibrations in air. They had sensitive hairs on their skin and carapaces that made them aware of the movements of water around them, including low frequency sounds. Some such as fish and cephalopods evolved sophisticated inner ears. To sing or call therefore was to invite death.
To this day defenseless or slow-moving animals are generally silent. Jellyfish, snails, worms, salamanders: These are all mostly silent beings. The species that sing are the creatures that can fly away from danger rapidly or defend themselves vigorously. These vocal species include birds, flying insects, jumping frogs, fast and well defended fish, and marine invertebrates such as spiny lobsters and crabs.
The first singers were likely winged cricket-like insects 280 million years ago. In the oceans, spiny lobsters or ancient fish like the ancestors of sturgeon might have been the first singers.
After these, evolution caused Earth’s songs became more and more diverse. Especially in places where visual or chemical communication was difficult or impossible, sound became a very important unifying communicative force with ecosystems.
Today, many ecosystems are of course extremely rich in sound, with varied soundscapes both night and day. What caused this great variety of sound? After all, if the function of sound is just to send a simple signal like “I’m here” or “stay out of my territory”, then a simple call or grunt with suffice. But instead we hear a world filled with marvelously diverse sounds.
Many factors contributed to this great diversification and those factors give us a hint at how life evolves and diversifies.
First, sounds reflect the physical diversity of the world. Birds that sing in dense forests tend to have a very slow, whistled, melodious songs. These are the kinds of songs whose sound waves transmit without too much degradation within dense vegetation. But birds that live in Open Country tend to sing with rapid whistles and trills, virtuosic displays that can pass from the bird’s mouth to the ears of listeners unimpeded by the reflections and reverberations imparted by vegetation. The same is true of fish and whale sounds in the oceans. Each one is adapted to the physical properties of the environment in which it sings. Even in the vibrational world of sound waves flowing through solid material songs seem to be adapted to their homes. For example, some insects sing not through the air but through the solid material of wood on which they stand such as the stalks of leaves or the trunks of trees. Every plant species has wood that has its own unique acoustic properties. The insects sing the song best suited to the plant on which they stand. So, when we listen to the varied sounds of the world we’re hearing a living manifestation of the physical variability of the world around us.
Another source of diversity in sonic communication is the need to avoid acoustic competition with other species. If every single insect and bird sang at the same time and at the same frequency they would smother one another’s sounds. Instead some of them divide up the acoustic Spectrum each finding their own channel through which to communicate with the others.
Predation can also act as a diversifying force in sonic evolution. By sounding different from other species prey animals can escape the attention of many predators. How? Because predators tend to learn the common sounds around them and home in on these to find that prey. sonic Rarity can be an advantage. This provides an impetus for diversification of sounds.
Many sounds of course serve as mating displays, communicating the location, identity, and quality of the singer. The aesthetic evolution that comes with sexual selection then comes into play, further diversifying sounds. Slight differences in the songs of closely related species or even of subpopulations within the same species can rapidly diverge from one another due to the aesthetic preferences of males and females within each subpopulation. Sexuality and its many extravagances is a creative Force for sonic evolution just as it is for visual displays such as the bright feathers of birds.
The great sonic diversity of the world acts as a glue that holds together many ecosystems. Sound therefore allows ecosystems to be more productive, resilient, and creative. How so? Through the connections that create possibilities. Think of all the animals that exist within dense subtropical and tropical forests. Many of these animals depend on sound for the success of their lives. Sound helps them to find food. Sound is the foundation of their breeding systems. Parents and offspring communicate through sound. Competitors mediate that interactions within ecosystems through sound. The soundscape also indicates changes in environmental conditions such as weather or the changing seasons. Without sound it is no exaggeration to say that many of these species lives would not be possible. And therefore the ecosystem functions that these species provide would also not be possible, such as fruit dispersal, pollination, herbivory, predation , and nutrient cycling. The forest exists, in part, because of sound.
We think often of the sensory world as ephemeral and somehow less important than so-called more fundamental things like genetics and the flow of atoms through ecosystems. But life is made from connection. Without connection death ensues. The senses connect. The senses , sound especially , therefore are a central part of the vitality and the future of ecosystems.
The sonic diversity of ecosystems also has practical use for conservation scientists. For decades we have assessed the health and vitality of ecosystems using acoustic surveys such as bird counts conducted by specialists taking nothing but their well-trained ears and a notebook into the field. These venerable field methods have lately been supplemented with the use of digital technology. We can now deploy microphones in ecosystems and record sounds for hours or sometimes even months at a time. This vast amount of data can then be analyzed through the use of computer algorithms that either seek out the calls of individual species, a form of pattern recognition, or by looking for overall statistical trends in the sonic data. For example, we can assess, using statistical software, how different types of forest management affects the overall sonic complexity of an ecosystem. This gives us an insight, through sound, into the functioning and diversity of these ecosystems.
These new methods are sometimes called passive acoustic monitoring and they have the great advantage of being relatively unintrusive and not harmful to the animals that are being studied, in contrast to more hands-on methods that require catching and manipulating living animals. But the passive nature of the recording also carries with it a danger. And that danger is that we will become experts in microphones and statistical software but forget to use our own ears and to listen using our own bodies to the many stories and wonders of the living world. A complement to technology has to be a renewed emphasis on the wisdom that comes from lived experience. This lived experience is that of professional scientific researchers, of course, but also and perhaps more importantly, the lived experience of the people who live within the ecosystems that scientists study. There are great stores of cultural knowledge and understanding that should be honored, listen to, and acted on, as a complement to technological or statistical forms of knowledge. There are multiple forms of Science in the world and the ecological crisis demands that we listen to all of them.
The sonic diversity of the world also offers us a way of communicating with people for whom conservation science might at first seem irrelevant or uninteresting. It turns out that human beings have amazing sonic memory. Perhaps because we communicate so much through spoken language our brains are excellent at remembering sounds. Our long-term memory for sound is much better, for example, then that of most of our close primate cousins. Therefore most people have a subconscious attachment to their homes or their places of origin through sounds. These sounds might be the particular sounds of a city street or of a farm field or of a forest, depending on where we grew up. Regardless of the kind of sound, these memories of the sounds of our homes stick with us for decades and if we hear these sounds later in life we are reminded of how the world used to be. This provides an opportunity for storytelling and connection. For example, I remember my grandfather, who has now passed away, telling me how the sounds of the Agricultural areas of the 1930s where he grew up what completely different by the time of the 1970s and 1980s. Many of the birds that he remembered as a young boy could no longer be heard in those fields. This was a result of the massive changes in agriculture in rural England where he lived. This story of diminishment has stuck with me through the decades. Why? Because it came from a trusted and loved family member. I have looked at hundreds of graphs of bird population declines and increases around the world but none of them have the same power over me and the same deep place in my memory as that story from my grandfather.
This suggests a reason why we might listen carefully in the present moment. By listening we ground ourselves in the sensory reality of the present moment and therefore we gain information that we can then relay to the Future. Our children, grandchildren, students, and neighbors will need our stories in the future. If we listen and pay attention now we will have stories that carry within them important messages about the nature of a changing world. And these messages will often carry more weight or at least be good compliments to the more dry and less emotionally powerful messages of data and graphs.
And so, I will conclude with an invitation to you. And that invitation is to pick a place somewhere where you live now and return to that place repeatedly over the coming weeks just to listen. This practice takes just a few minutes but it yields great insights. By returning again and again to a place with enthusiastically open senses we befriend that place and the sensory richness of the place, both its beauty and it’s brokenness, becomes known to us.
This direct connection with life is a source of personal renewal and meaning and often of joy. Listening can also be a great stimulus to curiosity. And curiosity is the foundation of all good science. What questions arise from the sounds that you hear at your place? How do the sounds of the place intersect with the questions that you already had within you as you arrive there?
You might also consider inviting a friend on this listening foray, sharing the sensory richness of the living world with another. We live in an age where we are saturated with an ever-increasing flow of PDFs and citations and messages from social media and stories arriving mediated by the manipulative algorithms of the electronic world.
Listening can rejoin us to the sensory richness of the Living Earth and reorient us back to the truths that emerge when we listen to what other species have to tell us.
Thank you for your attention.