Health
Visualizing the Evolution of Vision and the Eye
|
a.bg-showmore-plg-link:hover,a.bg-showmore-plg-link:active,a.bg-showmore-plg-link:focuscolor:#0071bb;
Roadmapping the Evolution of the Eye
Throughout history, numerous creatures have evolved increasingly complex eyes in response to different selective pressures.
Not all organisms, however, experience the same pressures. It’s why some creatures today still have eyes that are quite simple, or why some have no eyes at all. These organisms exemplify eyes that are “frozen” in time. They provide snapshots of the past, or “checkpoints” of how the eye has transformed throughout its evolutionary journey.
Scientists study the genes, anatomy, and vision of these creatures to figure out a roadmap of how the eye came to be. And so, we put together an evolutionary graphic timeline of the eye’s different stages using several candidate species.
Let’s take a look at how the eye has formed throughout time.
Where Vision Comes From
The retina is a layer of nerve tissue, often at the back of the eye, that is sensitive to light.
When light hits it, specialized cells called photoreceptors transform light energy into electrical signals and send them to the brain. Then the brain processes these electrical signals into images, creating vision.
The earliest form of vision arose in unicellular organisms. Containing simple nerve cells that can only distinguish light from dark, they are the most common eye in existence today.
The ability to detect shapes, direction, and color comes from all of the add-ons evolution introduces to these cells.
Two Major Types of Eyes
Two major eye types are dominant across species. Despite having different shapes or specialized parts, improved vision in both eye types is a product of small, gradual changes that optimize the physics of light.
Simple Eyes
Simple eyes are actually quite complex, but get their name because they consist of one individual unit.
Some mollusks and all of the higher vertebrates, like birds, reptiles, or humans, have simple eyes.
Simple eyes evolved from a pigment cup, slowly folding inwards with time into the shape we recognize today. Specialized structures like the lens, cornea, and pupil arose to help improve the focus of light on the retina. This helps create sharper, clearer images for the brain to process.
Compound Eyes
Compound eyes are formed by repeating the same basic units of photoreceptors called ommatidia. Each ommatidium is similar to a simple eye, composed of lenses and photoreceptors.
Grouped together, ommatidia form a geodesic pattern that is commonly seen in insects and crustaceans.
Our understanding of the evolution of the compound eye is a bit murky, but we know that rudimentary ommatidia evolved into larger, grouped structures that maximize light capture.
In environments like caves, the deep subsurface, or the ocean floor where little to no light exists, compound eyes are useful for producing vision that gives even the slightest advantage over other species.
How Will Vision Evolve?
Our increasing dependency on technology and digital devices may be ushering in the advent of a new eye shape.
The muscles around the eye stretch to shift the lens when staring at something close by. The eye’s round shape elongates in response to this muscle strain.
Screen time with cellphones, tablets, and computers has risen dramatically over the years, especially during the COVID-19 pandemic. Recent studies are already reporting rises in childhood myopia, the inability to see far away. Since the pandemic, cases have increased by 17%, affecting almost 37% of schoolchildren.
Other evolutionary opportunities for our eyes are currently less obvious. It remains to be seen whether advanced corrective therapies, like corneal transplants or visual prosthetics, will have any long-term evolutionary impact on the eye.
For now, colored contacts and wearable tech may be our peek into the future of vision.
Complete Sources
Fernald, Russell D. “Casting a Genetic Light on the Evolution of Eyes.” Science, vol. 313, no. 5795, 29 Sept. 2006, pp. 1914–1918
Gehring, W. J. “New Perspectives on Eye Development and the Evolution of Eyes and Photoreceptors.” Journal of Heredity, vol. 96, no. 3, 13 Jan. 2005, pp. 171–184. Accessed 18 Dec. 2019.
“The Evolution of Sight | PHOS.”
Land, Michael F, and Dan-Eric Nilsson. Animal Eyes. Oxford ; New York, Oxford University Press, 2002.
“The Major Topics of the Research Work of Prof. Dan-E. Nilsson: Vision-Research.eu – the Gateway to European Vision Research.” Accessed 3 Oct. 2022.
Health
RCMP warn about benzodiazepine-laced fentanyl tied to overdose in Alberta – Edmonton Journal
Article content
Grande Prairie RCMP issued a warning Friday after it was revealed fentanyl linked to a deadly overdose was mixed with a chemical that doesn’t respond to naloxone treatment.
The drugs were initially seized on Feb. 28 after a fatal overdose, and this week, Health Canada reported back to Mounties that the fentanyl had been mixed with Bromazolam, which is a benzodiazepine.
Article content
Mounties say this is the first recorded instance of Bromazolam in Alberta. The drug has previously been linked to nine fatal overdoses in New Brunswick in 2022.
The pills seized in Alberta were oval-shaped and stamped with “20” and “SS,” though Mounties say it can come in other forms.
Naloxone treatment, given in many cases of opioid toxicity, is not effective in reversing the effects of Bromazalam, Mounties said, and therefore, any fentanyl mixed with the benzodiazepine “would see a reduced effectiveness of naloxone, requiring the use of additional doses and may still result in a fatality.”
From January to November of last year, there were 1,706 opioid-related deaths in Alberta, and 57 linked to benzodiazepine, up from 1,375 and 43, respectively, in 2022.
Mounties say officers responded to about 1,100 opioid-related calls for service, last year with a third of those proving fatal. RCMP officers also used naloxone 67 times while in the field, a jump of nearly a third over the previous year.
Recommended from Editorial
Share this article in your social network
Health
CFIA continues surveillance for HPAI in cattle, while sticking with original name for disease – RealAgriculture
The Canada Food Inspection Agency will continue to refer to highly pathogenic avian influenza in cattle as HPAI in cattle, and not refer to it as bovine influenza A virus (BIAV), as suggested by the American Association of Bovine Practitioners earlier this month.
Dr. Martin Appelt, senior director for the Canadian Food Inspection Agency, in the interview below, says at this time Canada will stick with “HPAI in cattle” when referencing the disease that’s been confirmed in dairy cattle in multiple states in the U.S.
The CFIA’s naming policy is consistent with the agency’s U.S. counterparts’, as the U.S. Animal and Plant Health Inspection Service has also said it will continue referring to it as HPAI or H5N1.
Appelt explains how the CFIA is learning from the U.S. experience to-date, and how it is working with veterinarians across Canada to stay vigilant for signs of the disease in dairy and beef cattle.
As of April 19, there has not been a confirmed case of HPAI in cattle in Canada. Appelt says it’s too soon to say if an eventual positive case will significantly restrict animal movement, as is the case with positive poultry cases.
This is a major concern for the cattle industry, as beef cattle especially move north and south across the U.S. border by the thousands. Appelt says that CFIA will address an infection in each species differently in conjunction with how the disease is spread and the threat to neighbouring farms or livestock.
Currently, provincial dairy organizations have advised producers to postpone any non-essential tours of dairy barns, as a precaution, in addition to other biosecurity measures to reduce the risk of cattle contracting HPAI.
Subscribe: Apple Podcasts | Spotify | RSS | All Podcasts
jQuery(document).ready(function($) {
$(“#homesub”).validate(
rules:
first_name:
required: true,
minlength: 2
,
last_name:
required: true,
minlength: 2
,
email:
required: true,
email: true,
minlength: 2
,
state:
required: true,
,
role:
required: true,
,
“listid[]”:
required: true,
minlength: 1
,
messages:
first_name: “Your first name is required.”,
last_name: “Your last name is required.”,
email: “Please verify your email is correct.”,
state: “Your state/province is required.”,
role: “Your role is required.”,
“listid[]”: “Select at least one list is required.”
,
submitHandler: function()
$.ajax(
type: “POST”,
url: “https://www.realagriculture.com/wp-admin/admin-ajax.php”,
data:
action: “realag_cc_process_subscribe_onclick”,
form: “homesub”,
data: $(“#homesub”).serialize(),
,
dataType: “html”,
timeout: 30000,
error: function(response)
console.log(response);
,
success: function(response)
$(“#homesub”).html(response);
,
);
);
});
Health
Toronto reports 2 more measles cases. Use our tool to check the spread in Canada – Toronto Star
/* OOVVUU Targeting */
const path = ‘/news/canada’;
const siteName = ‘thestar.com’;
let domain = ‘thestar.com’;
if (siteName === ‘thestar.com’)
domain = ‘thestar.com’;
else if (siteName === ‘niagarafallsreview.ca’)
domain = ‘niagara_falls_review’;
else if (siteName === ‘stcatharinesstandard.ca’)
domain = ‘st_catharines_standard’;
else if (siteName === ‘thepeterboroughexaminer.com’)
domain = ‘the_peterborough_examiner’;
else if (siteName === ‘therecord.com’)
domain = ‘the_record’;
else if (siteName === ‘thespec.com’)
domain = ‘the_spec’;
else if (siteName === ‘wellandtribune.ca’)
domain = ‘welland_tribune’;
else if (siteName === ‘bramptonguardian.com’)
domain = ‘brampton_guardian’;
else if (siteName === ‘caledonenterprise.com’)
domain = ‘caledon_enterprise’;
else if (siteName === ‘cambridgetimes.ca’)
domain = ‘cambridge_times’;
else if (siteName === ‘durhamregion.com’)
domain = ‘durham_region’;
else if (siteName === ‘guelphmercury.com’)
domain = ‘guelph_mercury’;
else if (siteName === ‘insidehalton.com’)
domain = ‘inside_halton’;
else if (siteName === ‘insideottawavalley.com’)
domain = ‘inside_ottawa_valley’;
else if (siteName === ‘mississauga.com’)
domain = ‘mississauga’;
else if (siteName === ‘muskokaregion.com’)
domain = ‘muskoka_region’;
else if (siteName === ‘newhamburgindependent.ca’)
domain = ‘new_hamburg_independent’;
else if (siteName === ‘niagarathisweek.com’)
domain = ‘niagara_this_week’;
else if (siteName === ‘northbaynipissing.com’)
domain = ‘north_bay_nipissing’;
else if (siteName === ‘northumberlandnews.com’)
domain = ‘northumberland_news’;
else if (siteName === ‘orangeville.com’)
domain = ‘orangeville’;
else if (siteName === ‘ourwindsor.ca’)
domain = ‘our_windsor’;
else if (siteName === ‘parrysound.com’)
domain = ‘parrysound’;
else if (siteName === ‘simcoe.com’)
domain = ‘simcoe’;
else if (siteName === ‘theifp.ca’)
domain = ‘the_ifp’;
else if (siteName === ‘waterloochronicle.ca’)
domain = ‘waterloo_chronicle’;
else if (siteName === ‘yorkregion.com’)
domain = ‘york_region’;
let sectionTag = ”;
try
if (domain === ‘thestar.com’ && path.indexOf(‘wires/’) = 0)
sectionTag = ‘/business’;
else if (path.indexOf(‘/autos’) >= 0)
sectionTag = ‘/autos’;
else if (path.indexOf(‘/entertainment’) >= 0)
sectionTag = ‘/entertainment’;
else if (path.indexOf(‘/life’) >= 0)
sectionTag = ‘/life’;
else if (path.indexOf(‘/news’) >= 0)
sectionTag = ‘/news’;
else if (path.indexOf(‘/politics’) >= 0)
sectionTag = ‘/politics’;
else if (path.indexOf(‘/sports’) >= 0)
sectionTag = ‘/sports’;
else if (path.indexOf(‘/opinion’) >= 0)
sectionTag = ‘/opinion’;
} catch (ex)
const descriptionUrl = ‘window.location.href’;
const vid = ‘mediainfo.reference_id’;
const cmsId = ‘2665777’;
let url = `https://pubads.g.doubleclick.net/gampad/ads?iu=/58580620/$domain/video/oovvuu$sectionTag&description_url=$descriptionUrl&vid=$vid&cmsid=$cmsId&tfcd=0&npa=0&sz=640×480&ad_rule=0&gdfp_req=1&output=vast&unviewed_position_start=1&env=vp&impl=s&correlator=`;
url = url.split(‘ ‘).join(”);
window.oovvuuReplacementAdServerURL = url;
Canada has seen a concerning rise in measles cases in the first months of 2024.
By the third week of March, the country had already recorded more than three times the number of cases as all of last year. Canada had just 12 cases of measles in 2023, up from three in 2022.
function buildUserSwitchAccountsForm()
var form = document.getElementById(‘user-local-logout-form-switch-accounts’);
if (form) return;
// build form with javascript since having a form element here breaks the payment modal.
var switchForm = document.createElement(‘form’);
switchForm.setAttribute(‘id’,’user-local-logout-form-switch-accounts’);
switchForm.setAttribute(‘method’,’post’);
switchForm.setAttribute(‘action’,’https://www.thestar.com/tncms/auth/logout/?return=https://www.thestar.com/users/login/?referer_url=https%3A%2F%2Fwww.thestar.com%2Fnews%2Fcanada%2Ftoronto-reports-2-more-measles-cases-use-our-tool-to-check-the-spread-in-canada%2Farticle_20aa7df4-e88f-11ee-8fad-8f8368d7ff53.html’);
switchForm.setAttribute(‘style’,’display:none;’);
var refUrl = document.createElement(‘input’); //input element, text
refUrl.setAttribute(‘type’,’hidden’);
refUrl.setAttribute(‘name’,’referer_url’);
refUrl.setAttribute(‘value’,’https://www.thestar.com/news/canada/toronto-reports-2-more-measles-cases-use-our-tool-to-check-the-spread-in-canada/article_20aa7df4-e88f-11ee-8fad-8f8368d7ff53.html’);
var submit = document.createElement(‘input’);
submit.setAttribute(‘type’,’submit’);
submit.setAttribute(‘name’,’logout’);
submit.setAttribute(‘value’,’Logout’);
switchForm.appendChild(refUrl);
switchForm.appendChild(submit);
document.getElementsByTagName(‘body’)[0].appendChild(switchForm);
function handleUserSwitchAccounts()
window.sessionStorage.removeItem(‘bd-viafoura-oidc’); // clear viafoura JWT token
// logout user before sending them to login page via return url
document.getElementById(‘user-local-logout-form-switch-accounts’).submit();
return false;
buildUserSwitchAccountsForm();
#ont-map-iframepadding:0;width:100%;border:0;overflow:hidden;
#ontario-cases-iframepadding:0;width:100%;border:0;overflow:hidden;
#province-table-iframepadding:0;width:100%;border:0;overflow:hidden;
console.log(‘=====> bRemoveLastParagraph: ‘,0);
-
Media16 hours ago
DJT Stock Rises. Trump Media CEO Alleges Potential Market Manipulation. – Barron's
-
Media18 hours ago
Trump Media alerts Nasdaq to potential market manipulation from 'naked' short selling of DJT stock – CNBC
-
Investment17 hours ago
Private equity gears up for potential National Football League investments – Financial Times
-
Sports22 hours ago
2024 Stanley Cup Playoffs 1st-round schedule – NHL.com
-
News15 hours ago
Canada Child Benefit payment on Friday | CTV News – CTV News Toronto
-
Real eState9 hours ago
Botched home sale costs Winnipeg man his right to sell real estate in Manitoba – CBC.ca
-
Business17 hours ago
Gas prices see 'largest single-day jump since early 2022': En-Pro International – Yahoo Canada Finance
-
Art20 hours ago
Enter the uncanny valley: New exhibition mixes AI and art photography – Euronews