In conversation with Doctor Darren Croft, researcher, scientist, professor of animal behaviour from the University of Exeter in the United Kingdom, and the executive director of the Centre for Whale Research in the San Juan Islands. My first time meeting him was on a boat off for whale watching, which he was on as well, completing his research on whales. We started talking about all things orcas, and the incredible similarities between humans and whales, in the one thing that excites me the most – menopause!
I needed to know more and jumped at the opportunity to be able to continue our conversation.
Elizabeth: Thank you for joining us today. Let’s begin with the beginning. What excited you to study whales?
Dr Darren Croft: I got involved with this incredible study on a very special population of killer whales, of orca, the Southern-resident Killer Whales.
And back in the early to mid-70s, whales were taken into captivity, so they were captured for aquaria for the marine parks. At that time, people catching the whales suggested there were thousands or at least hundreds of whales, and there was no limit.
There were many dedicated biologists at the time who started to develop methods for identifying those whales. We can tell them apart because they have these unique markings. These orca, these killer whales, have a saddle patch behind their dorsal fin, and each saddle patch has this grey area, like a fingerprint.
So 1976, this long-term study started. I was about 6 months old when this study started. It's been going for nearly 50 years. Every individual in the population is individually recognized. We know all births and all deaths over that time period. It's just incredible.
Unfortunately, today, this orca population only has around 70 animals left and is in critical risk of extinction. So it's a very, very vulnerable population. How did I get involved?
Well, I need to rewind about two decades. At the time, I'd been working on social behaviour in some tiny little fish on the island of Trinidad, looking at how these little fish learn to recognize each other and cooperate together. And a student came and knocked to my office door and said I'd really like to do my master's thesis on this amazing population of killer whales.
So I supervised the master's thesis, and then over time, over the last two decades, the collaboration, the research grew and grew. We've learned so much about this amazing population of whales. And then sadly, the founder of the organization, Ken Balkin, who started this work in the in the 70s. He passed away a couple of years ago, so I've stepped in to help the nonprofit organization continue into the future.
Elizabeth: Hats off to all of you we know so much about these magnificent whales. We also recently went to see the whales at Monterey Bay, and we saw some amazing humpback whales, like, I think about 9 to 10 of them. They are so magnificent when you look at that and realise nature is so beautiful and it's so important for us to preserve.
All these mammals and all these animals and species, any particular memories that you have of interacting with whales? Have you touched them? Have you gone into the ocean with them?
Dr Darren Croft: We don't go into the ocean with them because they're highly protected, and we don't touch them. But I think in terms of sort of magical, meaningful, memorable experiences, one of the things that we've been working on with our research is looking at Lifespan and looking at how old these animals can get and how that relates to their reproductive lifespan. And so what's really special about this population is that females will have their last calf in their 30s or 40s, but have a life history very much like humans, where they can live for decades. After menopause, they live. They can live until they're 80 or 90 years old. One of my really special memories was a was a really special whale called J2. She was known as Granny. She was the oldest whale in the population for a long time.
I remember the first time I saw her. I'd been working with the data for a number of years before I got to see the whales in the field. I'd been collaborating remotely from here in the UK, and one of the things that we found was that the older females led the group to find food, and their granny was out in the front, leading her group around the coastal waters to go and find salmon. And it was just so magical to see that matriarch, see this whale who was approaching 100 years old and still with a really special role to play for her family, and keeping her family alive by helping them to find food.
Elizabeth: I mean, that is incredible because it does fascinate me, this connection between humans and whales. As the founder of Empress Naturals, we create products for women in perimenopause and menopause.
And one of the reasons I wanted to interview you was because of the fact that whales are one of the few mammals that experience menopause. That was completely fascinating for me. What exactly do the orcas do when they are in menopause? What are the traits that you see is very similar to a woman who is going through menopause?
Dr Darren Croft: Yeah. So that's a really good question. So as you said, there are over 5000 species of mammals on the planet and in our oceans, and actually only six go through menopause: humans, and then the other five are all whales, and they're all whales that have teeth. So they're all tooth whales. Humpback whales don't do it. The baleen whales don't do it. The filter feeders are all tooth whales. And so killer whales, short-finned pilot whales, narwhal, beluga, and false killer whale are the only non-human females on the planet that go through menopause. It's incredible.
So natural selection and evolution in most mammals is selected and most animals is selected for males and females. Females are talking about here to maximize their reproductive success by having as many offspring as they can. And that means that in all of the primates, apart from humans, females will reproduce until the end of their lives. What's really unusual about these species of whales is that they terminate reproduction far earlier. They have their last calf far earlier than they can expect to live, and that's similar to humans. We know that they physiologically terminate reproduction, so we know that physiologically these females are no longer cycling, so they're no longer reproductive.
We don't know anything about how it affects them physiologically. What we do know is the role that they play in their family group and how that changes as they get older. One of the key things that happens in these whale societies where females go through menopause is that they become absolutely central to the success and survival of their family group. These older matriarchs store knowledge of where to find food. They're central in their society, and if they die, their offspring and grand offspring have an increased risk of dying. They simply help their group find food. Not only that, they share the food that they find with their family group. So we can't say anything about what their physiological experience is, but what we can say is just how important they are in their society for helping their grand offspring and their children, their offspring, survive.
Elizabeth: This is so true with human society as well. I mean invariably. Of course, I'm not underestimating or undermining the value of the grandfather, but having the grandmother there is a big support.
Dr Darren Croft: So you see this pattern also amongst the killer whales and the orcas. There are three key kinds of hypotheses.
The main driving one at the moment is that grandmothers helping their offspring reproduce and provide care for the grand offspring, which can increase the survival of the grand offspring.
There's also another hypothesis, which is actually that it's mothers helping to care for their last dependent offspring, and that doesn't seem to be important in humans. Actually, in human societies, the mother's role is really important until weaning.
And then, actually, other members of the family are able to provide care if the mother isn't able to provide care. What's different about the killer whales is that the sons are absolutely dependent on their mums for their survival, their entire life. They're absolute mummies boys. So you can have a 30-year-old male who's swimming alongside his mom, and his mom's catching fish and feeding him fish. They are bending to their mums for their survival. So and that we don't tend to see that in human societies. In the orca societies, the killer whale societies, it really seems to be important that males are with their mums and mums provide these survival benefits to their sons.
Elizabeth: So what about the young female whales? Do they catch their fish on their own? Do they hunt on their own?
Dr Darren Croft: It's a really good question. And so we haven't done a detailed analysis. We're just doing that now, looking at patterns of foraging. The research team has been flying drones over the whales. So we can actually see who's foraging and who's catching fish, and who's sharing fish.
What we do know what happens is that when females start to get a calf, their own calf, their social bond with their mom weakens, but they still live in the same family group. So one thing that's really unusual about all these whales that go through menopause is that they have a very unusual social system where both sons and daughters stay in the family group, so there's no dispersal, or there's very little dispersal if any. So they have this matriarchal society where sons and daughters live in their mum's group. What happens is that when daughters start to reproduce, they're still in the mom's group, but their relationship with the mom kind of weakens.
There's a reason for that. What happens in reproduction is that males will mate with females from different groups. So when a son has a successful calf, there's no new mouth to feed. Another group is caring for that calf. The son has mated with a different family group and then comes back to his mom. If a daughter reproduces, there's another mouth to feed in the family group. There's another calf. Like when females are lactating, they need about 40% more salmon. So from an evolutionary perspective, these post-reproductive females can have more grandchildren through their sons. A daughter can only have a calf once every four years.
Whereas a son has multiple calves in a year with different females in the group. So mums put all of their energy in late life into their adult sons because that's their ticket to maximizing the number of grand offspring that they can have.
Elizabeth: Wow, so amazing.
So another question is what makes menopause in orcas so evolutionary and so significant?
Dr Darren Croft: Yeah, so because it's so rare, because for a long time we thought that menopause was only in humans. Like I said, there are over 5000 species of mammals, so why has this evolved? Why is it so rare? We can learn a great deal by asking questions about how menopause evolved in whales and then comparing that to patterns of menopause in human populations.
We find the same general mechanisms of menopause across these very different species between humans and whales, that it's where these grandmothers can play a really significant role in helping their family group, helping their group survive.
What's fascinating about the whales is they actually live these species through menopause, live 40 years longer than they're expected to, given their size and their ecology. So just like humans, if we compare our lifespan to our closest living primates. We live longer than our closest living primates. So what's happened is the age at last reproduction hasn't really changed. It's the total lifespan. So menopause evolved by living longer and we find the same thing happens in the whales. So it's a really fascinating comparison for us between human evolution and the evolution in the ocean of these very socially complex species.
Elizabeth: I guess then I wonder, why do you think as a scientist and researcher that menopause only evolved in whales, but not in most other animals?
Dr Darren Croft: Yeah. So that's a really good question. So and and if we look, if we look at some examples, there are grandmother benefits in other animals that don't go through menopause. A great example is elephants. So in elephant societies, the matriarchs increase the survival of their grand offspring. It's well documented that they know where to find water in times of drought. They know how to resolve social conflict.
What's different is, well, there are two different things. One is that they don't have their sons with them, so they don't have their sons dispersed, so they leave the family group before they reach sexual maturity. So they don't have that mechanism to really invest in the sons, which can maximize the number of grand offspring that they have. They also don't have the same opportunities to help. So a key thing about these whales is they're the fish-eating whales, they're catching fish and sharing them with their family group. In elephant societies, they browse and graze from trees. It's not like they can help their family graze more. They can't share. They don't have the same social structure, and we think it's the social structure, that really unusual social structure, which is key. But then also, there needs to be a mechanism by which all the matriarchs can help, and that they can increase the survival of their offspring and grand offspring. There needs to be the opportunity to be able to provide and provision in a way that you can't do if you're reproductive. And so it's not just about sharing knowledge, it's about actively transferring resources.
Elizabeth: That is the same amongst a lot of women that I meet for whom menopause signals the end of fertility and youth, and some women get depressed, anxious, they don’t like this phase of menopause. So what does your work suggest that it actually marks the beginning of for whales?
Dr Darren Croft: Yeah, definitely. So if we look at the killer whale societies, females play a really fundamental role in their family. They're switching from a strategy of having their own to one where, without them, their family won't survive. Without them, their descendants will die. It's not simply that they've reached a point where they no longer have a purpose. They have just reached a different point in their life where they are then helping others, they're helping that wider family group. And it's really, really important that they're there, and they must be able to share their knowledge of where to find the fish and all the other important things.
Elizabeth: Is there any evidence of psychological benefits like resilience, calmness in menopausal veins, as you feel? I don't know if there's any study to see how their temperament has changed.
Dr Darren Croft: So it's really tricky because we are not able to do experiments on the whales in the wild and whales in captivity, unfortunately, but it's unfortunate that they've ever been in captivity because they will not express normal behaviour. So we can't really learn anything about normal behaviour for animals in captivity.
All we see is the role that they're playing within their society, that they emerge as the leaders, they emerge as the essential figures in their society in terms of their temperament or changes in behaviour through time.
Elizabeth: You mentioned that five types of whales go through menopause. Can you name them? And how do you know it’s just these five?
Dr Darren Croft: We've done a lot within our research group here, analysing the age structure. Actually, we can tell the age of these whales by growth rings on their teeth. Their teeth grow like trees. Scientists can count how many growth rings there are in a tooth of whale. So using that data and also looking at their reproductive history, we've been able to assess which types or which species go through menopause. So, of all the data we've been able to get, there are only 5 species of whales or five non-human species that go through menopause.
So it's the killer whales, the short-finned pilot whales, the beluga, the narwhal, and the false killer whale. Their females go through menopause. Females will reproduce until the end of life at a species level.
Elizabeth: Another question I have is, if there's one grandmother who is going through menopause, how many whales are there in her care at any given point on average?
Dr Darren Croft: So that's a really, that's a really good question. It's very variable. It could be, it could be very small, or she may have, you know, 20 or 30 whales in her pod, so she could have quite a small family match line. It's very variable in the history of the family, how many offspring have survived.
But also, what's also very fascinating about the orca, the southern residents, is they live in what we call a multi-level society, and humans do as well, where we have friendships at different levels. So we have our local family, then we might have friends in another community. So in the killer whales, they have the Matra line, which is their family group. These Matra lines organize into pods so that a pod has multiple Matra lines, and these pods organize into a community. So the Southern residents have three pods.
And sometimes they all come together and socialise the entire population, the entire community, all three pods come together at the same time. So they're really well connected in this kind of multi-level society.
Elizabeth: Now the question is that are the grandmothers whales friendly with each other?
Dr Darren Croft: Yeah, it's a really good question. We don't know. So, we're just starting to be able to look at those kinds of social relationships by looking at this using the video from the drone.
And so we're really interested in how these grandmothers, how these matriarchs form social relationships both within their group, but also across and outside of their group. How important are they to connecting families? How are they important to connecting the match alliance?
We don't know. Give us some time, and I am sure we'll be able to answer that question.
Another fascinating orca menopause fact is that we often look at where the teeth of the whale scratch another whale, which leaves these scars called rakes. And so we looked at whether or not males were more likely to get more scratches or fewer scratches when their mum was alive or when she was dead.
What we found is that sons who have that post-reproductive mums so the matriarch that's gone through menopause when she's still around, he gets a lot less of these rakes. So the conclusion is he's getting beaten up less by other whales. And so their brothers are also helping their sons kind of navigate and avoid getting into trouble.
Elizabeth: What is it that you'd like to tell our readers? How can they help the Centre for Whale Research?
Dr Darren Croft: Yeah, so I would encourage everyone to visit the website. Learn more about these whales, learn more about this incredible population, and just how special they are. Their unique behaviour and how sad it will be if we lose them. And we've got suggestions and some guidance on the website of things people can do, of politicians to contact, of action people can take, and how they can support the organisation in its work to try and help and protect these whales.
But it ultimately is things we can all do in our everyday lives. Protecting, conserving, caring about our environment, making, making environmental choices with everything we do.
RAPID FIRE QUESTIONS WITH DR. CROFT
E: Three similarities between a grandmother whale that goes through menopause and a woman.
Dr C: Three strong traits: knowledge, leadership, and wisdom.
E: Tell us a particular trait that is similar to whales that goes through menopause and a woman in menopause.
Dr C: The grandmother can play a role in keeping their grand offspring healthy and alive.
E: Where does the grandfather whale fit in this or in the structure? And do they live as long as the female whales?
Dr C: So grandfathers are never around the grand offspring. So, yeah, so they do go MIA. They're always MIA. Yeah. So it's always grandmothers who are with the offspring.
A grandmother whale, or the whale that's in menopause, lives for almost 40 to 50 years after their reproductive years. Yeah, whereas actually males tend to only live into their 30s. The maximum lifespan of a male is 60, and many typically die in their 30s. So males have a much shorter lifespan than females.
E: How do they die? I mean, what's the reason?
Dr C: They often die when their mom dies. We know that their moms are really key in
feeding them and helping them get food. But we rarely find a dead whale, so we can rarely determine the cause of death.
