Skip to content

Nature

Intriguing leadership roles in orcas linked to evolution, even in humans

by Dave Armstrong 12 Jan 2017
Intriguing leadership roles in orcas linked to evolution, even in humans

The ecotypes of killers live in many places around the globe, with Hebridean population decreasing (our story from the "West Coast Community" is at: Orca's Hebridean Overture, while Norwegian, Icelandic and several Pacific communities prosper rather better. This enthusiast is in the Antarctic enjoying the provision of ample food supplies in the form of Weddell seals in the Weddell Sea!

Weddell Sea orca image; Credit: © Robert Pitman/NOAA

Public appreciation of orcas as the killer whales should now include a remarkable similarity to the life-styles of humans themselves. Grandmother orcas are one of only 3 species (the other one is the short finned pilot whale, Globicephala macrorhynchus) that become menopausal. This restriction on reproduction is associated with increasing fecundity of daughters in a species. The female orca for example is less successful at breeding than her daughters when they reach reproductive age at around 15 years old.

Selection ensures that a role for older females must be found if they are to survive and Lauren J.N. Brent and her 5 colleagues have gathered an extensive dataset to investigate this. The paper also determines whether grandmother orcas lead groups around their traditional Chinook salmon (Oncorhynchus tshawytscha) fishing grounds. They publish their open access paper in Current Biology from the Universities of Exeter and York, UK, and the Center for Whale Research in Friday Harbor, Washington, US under the title Ecological Knowledge, Leadership, and the Evolution of Menopause in Killer Whales.

Rather like humans, female killer whales, breed between the ages of 12-40 and live into their 90s. Males rarely survive beyond their 50s! The maternal group is the most significant for the whales, with sons even more likely to follow their mothers than daughters. When the salmon don't turn up, the orcas can die off, especially without leadership. After analysing 751 hours of video off the BC and Washington coasts, studying activity during the annual summer salmon migrations of 2001-2009, the leadership of groups was established. 102 individual orcas were also observed in records dating from 1976 to determine relationships.

Older females (over 35 years-old) were more likely than adult males to lead especially when the salmon numbers were low. We have known for some time that adults benefit from their mothers' presence, with mortality increasing significantly after the mother's death. Sons have higher reproductive potential than daughters, with much greater fitness benefits, but daughters live longer, giving greater potential over time. Undoubtedly, though, sons rely on mothers while all whales follow post-reproductive females at times of low salmon abundance.

Ecological knowledge within the old females plays a large part in orca survival. When the fish don't run, natural selection plays for the grandmothers who know where they have found food in years gone by. The authors claim that preliterate humans would also use the old for information in situations such as drought. We can't deny that social interaction also plays a part in both orcas and humans. Recent work on the functions of older elephant (Loxodonta Africana females could shed more light on how experience plays a part in the assessment of and solution to problems.

Real interest now lies in how other orca ecotypes use their social structure and whether menopause occurs and then lays a part. Do they help particular relatives, especially their sons and thereby evolve the menopause?


Trending Eco-Friendly Clothing

Love My Planet Women's Relaxed Fit Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Love My Planet Women's Relaxed Fit Hoodie
Love My Planet women's eco-friendly relaxed fit hoodieSize Guide Centimeters 8 10 12 14 16 18 Bust 84 88 92 97 103 108 Waist 66 70 75 80 85 91 Hips 91 95 99 104 109 116 Bust: Measure around the fullest part of...
£38.00
£38.00
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Earth
Quick Add
Close
Notify me
Notify me
Penguins Hate Push-Ups Men's Pullover Hoodie
Penguins Hate Push-Ups men's eco-friendly pullover HoodieSize Guide Centimeters XS S M L XL XXL Height 171 175 179 183 189 195 Chest 86 93 99 104 116 129 Waist 71 76 81 89 99 112 Chest: Measure all round your chest just below...
£38.00
£38.00
Close
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Earth
Quick Add
Close
Notify me
Notify me
Notify me
Lightning Bolt Kids Long Sleeve T-Shirt
Lightning Bolt kids eco-friendly long sleeve t-shirtSize Guide Centimeters 3-4yrs 5-6yrs 7-8yrs 9-10yrs 11-12yrs Height 98 112 125 136 147 Chest 60 66 70 75 84 Chest: Measure all around your chest just below your armpits. Height: Your natural height If you fall between...
£18.00
£18.00
Close
Notify me
Notify me
Notify me
Union Jack Tote Bag
Earth
Quick Add
Close
Notify me
Notify me
Union Jack Tote Bag
Union Jack eco-friendly colour tote bagProduct Specification Organic Cotton Tote Bag. Twill Weave (170gsm). 37 x 42 cm (7cm gusset.) Made in India / Designed on the Isle of Wight. Wash Cool, Hang Dry.
£16.00
£16.00
Close
Notify me
Notify me
Prev Post
Next Post

Eco-Friendly Shop

Women's Clothing

Eco-Friendly Clothing for Women Our online shop offers a wide range of sustainable women’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Men's Clothing

Eco-Friendly Clothing for Men Our online shop offers a wide range of sustainable men’s clothing products, including t-shirts, hoodies, vests, sweaters, shorts, and...
Shop Now

Kids Clothing

Eco-Friendly Clothes for Kids Our online shop offers a wide range of sustainable kids clothing products, including t-shirts, hoodies and jumpers. Our garments...
Shop Now
Someone recently bought a
[time] ago, from [location]

Thanks for subscribing!

This email has been registered!

Shop the look

Choose Options

Earth Times
Sign up for exclusive updates, new arrivals & insider only discounts

Recently Viewed

Edit Option
Back In Stock Notification
this is just a warning
Login
Shopping Cart
0 items

Before you leave...

Take 20% off your first order

20% off

Enter the code below at checkout to get 20% off your first order

CODESALE20

Continue Shopping